Let's see.

HD textures
Been a while since I want an upgrade of textures, I feel that many equipment got more pixels but we're not quite exactly here.

Job design actually complete
Dark Knight Living dead, TBN, Oblation, Enhanced Unmend, pet with a questionable AI, Darkside virtually inexistent.
Machinist Flamethrower, questionable AI, utility in the strawberries and no damage to back it up.
Gunbreak very rigid continuation.
Ninja getting a rework every X.1.
BRD.
Summoner.

Many jobs have a gauge for... ONE button.
Everyone asking for SQEX to not dumb down a job, it results in the job being 2 button mash and/or a very rigid mess.
I'd like for SQEX to stop adding jobs or limiting themselves to 1 and complete the existing jobs. Don't make the job appealing to the casuals or the hardcore, make the job appealing to the one who plays/want to plays this job due to thematics/mechanics.

I won't complain about balancing, because at least there is no actual dead job, just less popular one.

Small party hard content
Asked for a long time, I wish they would add hard content such as Delubrum Reginae Savage but not 48 players please avoid large scale hard content higher than 24 players.
Savage dungeon with a timer for cool rewards for example. Something that makes gear acquired in savage worth using somewhere else.

Content to improve yourself
The game takes the player hand way too much.
There are quests where people complains about it being too hard, I'm not an exceptional player, I'm closer to a human body piloted by 3 monkeys and there is no hard quests to me.

More puzzles
It's great that we got sniping mini games, traveling with X NPC quests, tracking quests...
But I'd like more puzzle like the one in Sharlayan. Even more, find a combination, complete a circuit, things that can be done by the UI team.
You know, rather than make huh... Stickers.

Communication about development
Liveletters are great, Yoshida shares a lot of information. But I feel that feedback was often ignored.
Blood weapon and Hypercharge not on a stack system, Livind Dead, TBN are really the most popular and relevant feedback I can think about.

IMO, XIV is a great game with big roughs spots.
The story shines, the music shines, the universe shines... But there are things like job design left in the shadows.