Here are several thoughts I have had and ideas for how to fix them. I have played since release and have played over 580 hours with a few hundred $ invested and focus on 1 mains and 1 support main with an infrastructure of another 4 chars for farming things for them. Then more lower ilvl alts. Normal for a future raider. Most players raiding have roughly this time and money investment I have found. Here are thoughts and critical problems with the game and my thoughts on fix.
When resurrecting, the player is immobile for a moment during which mechanics are often cast. The player is then despite skill unable to dodge mechanics that are being cast during the ress.
Fix: The grace period after resurrecting should be a couple of seconds. Recommended: 3-4 seconds invulnerability after accepting a res, which is canceled if dealing damage to a foe so it cant be readily abused.
Poor telegraphing and often undistinguishable patterns: of in particular lower tier raids. Make things slightly more punishing to fail but please make them clearly distinguishable from one another. Seriously. Several of your encounters have triggered abilities that look almost identical and combined with short reaction times, low and medium skill players always fail. This needs to be adressed it is a serious gameplay flaw in your core design. The abilities that heavily punish players must be distinguished easily from eachother and preferably from other abilities. This does not make it easier but it makes your players feel less bad, feel less confused as to wtf is going on and feel better because they saw what was coming and avoided it. This is already in the game but many of the bosses, and in particular earlier bosses simply dont really show what they are going to do and the animations does not reflect what they are going to do.
Short reaction time events. Many casts and effects in general are extremely quick which really kills it for players without higher then average reaction time. My recommendation is to increase cast times slightly on all lower tier raids. They are for practicing, not making the average player feel bad. Currently on tier 1-2 raids, every 4th blue aura cast is interrupted, possibly less. The cast time on interrupts is often atleast half of the cast time which makes this difficult. For casual content, a cast that needs interruption should be way longer than on high difficulty content. This is a good practice that should be upheld.
Counters: Different timings on all counters. Some are inarguably worse. Fix this. It does not belong in a competitive game.
Guardian raids mostly: Extremely poor replayability but forced repetitive gameplay. You force us to clear chaos dungeo and guardian raid twice a day and you force us to play on multiple characters unless we want to play the latest raid before christmas. Now. Why does a guardian raid take like 12-13 minutes a lot of the time and even often fail? This is poor design and is a flaw so bad that many of my friends have quit and I might too. Being forced into repeated gameplay isn’t bad. I feel my character improve. But that it takes me 4 hours to clear chaos dungeon and guardian raid on my 5 characters is ridiculous. You literally advertise that you want the players to play 10 hours per day to even clear half of what is needed to reach the endgame within a month or two.
Solution: Why is the hp of these bosses so high and why do they keep teleporting away? I just fought a guardian raid where our dps wasn’t the best. I played support and what cost time was that it literally teleported away from us 4 or 5 times. This has got to be fixed. Change so they only can teleport away once and reduce the HP of the bosses. If unlucky with teleports it can EASILY take over a minute to reach the boss location from the last location. This is a joke and needs to be adressed. Your players will love you for making guardian raids shorter. They are not endgame content. They are levelling. Farming. Repetitive. All players not only should do them but must do them and many times to be able to progress, thus your players needs to kill this incredibly simple and timeconsuming event thousands of times. Please. Reduce this time so they have some time left to experience the rest of the game which I think is fantastic but dont have enough time for. Dont nerf endgame high difficulty content.
Climbing: Please only use climbing in circumstances
Cutscenes: Why have long story cutscenes in the middle of the dungeon? Please have the epic big climax where the boss dies after so we do not have to wait 5 minutes+. The long cutscenes should be before and after, and only short cutscenes during party dungeons. Else make them solo dungeons. it feels more epic for newer players anyway.
Events with disguises etc: should be checkpoint based so you do not have to redo the last 10 minutes of gameplay if failed.
Unit collisions sets speed to self and stops you midjump. Jesus. This is so annoying. Make collisions with speed sort of glide along the wall. Try how it works in other MMOs/RPGs. I have had the cerberus mount with double jump feature and since I started playing on released day, I have played 16 hours per day and till this day I have yet to complete 1 double jump without getting stuck on an (often invisible) wall and stopping in my tracks. Please, try jump through some doors, next to some small rocks or through a tunnel. It is impossible and needs to be fixed. This is broken and poor physics design. I cannot defend you in any way for this. Someone must have noticed this during QA and this is arguable the only physics that have bothered me much.
Currencies: There are just way too many currencies. This is fine but leads to obvious problems. Giving new players choice currencies is bad practice as they have no idea what they should do with them. Just give them a useful starting currency instead in the one time things. For future content, keep new and further currencies to a minimum. Think of polygons or similar. Having more adds strain to the system. It creates friction and frustration in the long run so when possible, keep them fewer. Achievement points, reputation levels and other things are better and use no currencies and are easily trackable and it’s obvious what they are for if you list the rewards.
P2W Currency conversion: Dollars <-> Royals <-> Crystals <-> gold is a too difficult value conversion to make in your brain so they struggle figuring out the actual dollar value equivalence to an item. I know this is on purpose, but having blue gems and royals is absolutely without purpose and is only to confuse ppl and make them lose track of the actual value of things.
Furthermore adding salt to injury is the fact that you use poor metrics when trading them in the currency trader. Not 100 royals etc but an odd value just 237 for example. This makes the calculation even more of a struggle and completely needlessly. This is also to make a direct calculation require trigonometric-compatible quantum brain. I understand the reason behind it. We all do. We dont need it. You do not want us to need it. This is actually toxic, truly.
Elevators: Jesus christ. Just wow guys. In no other game have I been frustrated and annoyed by a feature like this. Some elevators are MINUTES away and I have a snail on the side of my apartment building that is faster. Please fix the worst ones! 
Pegi13 and down. Seriously, please dont tell me that this game that directly suggest using credit cards for features vital to the game is directed towards kids. Now then. Why do you censore this game? If grown enough to have a card, they cant handle seeing some extent of skin? We’re not talking nude here. I demand no censorship. It is ridiculous. This game is, and should be, aimed towards 18+ with credit cards for obvious reasons. Any attempts at targeting younger non-adults is dishonest and dishonourable.
The music at sea is great. Fantastic 10/10 I love you. Tooki island too. More of this please.
P2W elements:
We know. The game is pay to win. While I dont mind. Please add more focus on paying for cosmetic improvements, small other things and the monthly aura. Quality of Life is something all players need to even stay in the game so most of Quality of Life should be available for all players. Please. You will lose 75% of all customers within a couple of months if they feel they are required to pay more than aura and another 40-50$ per month worth of quality of life for a feasible raiding environment.
Follow examples of major actors in the business. FFXIV sells billions worth of skins and stuff. Dont make people pay for all the other quality of life. Quality of life is everything in a game like this. I will throw money at the screen. Make the game accessible to all players, with only small p2w & VIP elements. Dont make ppl feel like the game is overly gated and constricted for not paying. I know frustration is a great way to make ppl pay but please, my friends are quitting the game one after another right now because they feel you must pay to remove natural gates that prevents convenience. Focus on monthly aura + aesthetic improvements for future released content. It is a winning concept and desceptively good money, this is proven across multiple platforms of sustainable MMO cultures.
Rapports:
When you talk to a rapport, you should directly at that screen see what the next few rewards are and at what levels you get that kinda stuff.
The bots: lets not even talk about this. You know what is needed. 95 out of 100 players currently levelling are currently bots. There is an actual train of ants moving through the levelling stones all called like Xchnaujhasfoi, all berserkers & sorcs and just noclip speedhack through the game. Must be some way to reduce this
T1 & T2 content needs nerfs: This is levelling content. Please nerf it. Controversial? No, everyone will run past it. When I play this content, despite carrying quite hard, I must play alone. If I do not play alone, 80% of all abyss raids are a futile spree of wipes and 40% of all guardian raids wipe. 90% of all guardian raids on the “hard bosses” wipe. Seriously. This is a levelling stepping stone. People are running past these and force us to spoon feed them through fights they cant handle. The fights are too hard for average players. You MUST watch guides, bring a decent build and learn the patterns on the boss to have a chance. If you had decent telegraphs they might have made it, unfortunately you dont.
Thus, these t1-t2 fights are overly difficult and often 12 minutes+ long. Even if they dodge 8/10 attacks they still die 4 times in 5 minutes and we have no resses left. No seriously. That is how public guardian raids are atm. I beg you to please nerf t1&t2 content to make them easier to plow through as we need to clear them over 1000 times this year. That is a serious number btw, if you have 5 characters you will need 1000 guardian raids to gear them up. Please dont exhaust and bore us out.
This would give relief to some of the most repetitive content. One option is also to make us only do 1 per day and double the reward or something. This is just too much.
Action bars: Bars invisible while strong hold or ship bars up: Your hotkeys for for examples songs and mount still work despite bars being gone. These bars are needed and must be diplayed by default. What is up with that?
Guardian raid:
- No health bar. Why? This is poor and I dont know if we are at 20% and 80% as I dont know how much damage the rest of the party is doing. I have sometimes sat alone left swinging for like 5 minutes only to find out there was still 25% left. The rest had apparently done nothing I guess. Please, give all bosses healthbars or other clear indicators of rough HP that are intuitive. Wounds. Colours. HP bars. Anything. Getting the % linked after is just sad. That they dont have an HP bar is only a detriment and does not benefit the players or the content in any perceivable way.
Animations: People cheer in a fantastic scene of joy and feast after a victory. Or a romantic scene where thirain sais something. Camera turns to my character who has a resting bitchface in stone. Now what is up with that? The lack of any sort of emotion or expression is disturbing in these scenes and really ruins them. They are great in all other aspects. Even the other characters sometimes smile towards you. But your character does not care. Zero emotion. Give my character a happy mokoko emote above it’s head or please make it smile or so 
Unannounced maintenance windows that lasts until maintenance: This is a big one because this game is a huge time investment. I have scheduled for exampled that I farm certain things on the morning before maintenance on three of my characters. Things that are VITAL to just keeping up with the game. For some that can play all hours on the day and for those who invest a lot of time - 80% of players - it is extremely important that you let them know a day in advance or keep the window short and during the middle of the night. This is how all serious organizations does it. You need to disturb the production as little as possible. A sudden patch should be advance notice as much as possible and done during the night (2am to 6am). I work with IT and schedule these types of emergancy maintenances every week. There is customer outrage when you announce it during the night and the maintenance is during the day. It is a catastrophy. Never do this. I have friends who have lost important daily activities or even weekly activities because you announce during the night and then have a maintenance from 8am to 11am when the reset is. This is HORRIBLE practice and must stop. Atleast have it like 6am-9am then so there is a small space to emergency prioritize and complete there most important things. Between 2am and 6am are the best hours for this type of job though and requires less advance notice as fewer play.