I want to start this post off by saying that if anything I am about to say has been covered in the past, then I apologize now. Thanks!
I have played FFXIV since its rerelease in 2013 and throughout the thousands of hours I have invested into this game, it goes without saying that the formula has become slightly stale. There are many things I love about this game, but after 10 years, the flaws, if not addressed, I believe will continue turning people away. I will address them below:
1. Dungeons. I love the dungeons, but they have all devolved into 3-boss encounters and now you're done. I suspect this was due to the player base complaining about how long some of the early dungeons were. The problem this creates is that the dungeons are now too streamlined. On top of this, most dungeons are one and done. You will never play them again, unless they happen to be the current max level dungeon, or they randomly pop up in the leveling roulette. A fix to this would be to make (Hard) versions of every dungeon as new expansions arise. This ensures that all dungeons are viable when at max level.
2. The Process of "Gearing Up" for Raiding. This is the most annoying part of the game in my opinion. There are SO many ways to acquire the gear you need to begin raiding. I could go on the market board right now and buy an entire set of gear at ilvl 640 and be ready to jump into raiding. It makes the process so quick that it's one of the reasons that endgame content feels like it is over so quickly. Also, the tomestone system needs to go, permanently, with the exception of poetics. In it's current state, it only serves to keep people on long enough each week so they can get their 450 tomestones of whatever variety is most current, and that's it. I believe the gear should be spread out amongst the various dungeons and crafted gear should be limited to maybe a couple armor pieces and a few accessories. This would drive players to replay dungeons to acquire gear, a very similar model to how WoTLK and TBC worked in WoW. I want to note that I am specifically referring to gearing up for raiding here. I think the gear distribution system once you begin raiding to be excellent.
3. The Glamour System. Now this is something that I know people have complained about. Since glamour is what many people call "the true endgame," why after 4 expansions do we still have to manage inventory space for glamours. Glamours should be permanent on your account once you acquire the weapon/gear.
I would like to hear what all of you think could be improved as well.