2 big things keep me from playing XIV currently.
Rigidity, virtually everything about XIV feels weird and clunky.
Open world feels awkward and limiting (tons of invisible walls.) Tons of loading screens because every zone is disjointed, can only imagine how bad it is for people without SSD's/Console players.
Everyone has the same animations/height/body-structure, only Lalafells look really distinct and it feels like all of the character budgeting went into them and Miqote to a lesser extent.
450 Tomecap feels super outadted, especially since the cap doesn't increase as weeks go on, directly punishing you for not capping for the week. As trivial as it might be to cap, its still dumb.
Over-reliance on instances, but having them be clunky as well. having to leave the instance to replace party members, every instance having a time limit. This was rather disruptive when trying to prog.
Bad UI/Inventory, having a cap on glamor dresser, the aesthetician being inconsistent and mostly useless. No way to increase inventory, forcing useless items into your bags with no toggle.
Rotations being janky, I don't think XIV is hard at all presently, and when I see people discuss the gameplay its mostly them talking about how clunky gamedesign forces you to play around it in dumb ways. Biggest example being tank-mitigation and how snapshotting works, I don't think manipulating the game's terrible latency engine is particularly skillful even if it does take good timing to pull off.
There are a lot more things, but when I raided hardcore and thus played often these really stood out to me. Felt like I needed a ton of plugins and shaders to make the game playable.
The second thing being its terrible content schedule.
Feels like the only time XIV is worth playing is the start of an xpac and the X.5 patch due to how glacial the game moves forward. Waiting months and months for basic content and balance fixing is terrible. Especially when often times content doesn't even release on patch and instead you're forced to wait even longer.
XIV is a good game, but to me its terrible to play regularly because of the above, seems best played in short bursts. WoW has struggled with this too, but recently has been very good for near constant entertainment, and being able to buy a sub with gold helps too.