I'm a roleplayer, so for me... so in that aspect, the biggest answer of it all is this: more customization.

1) XIV's character creation screen at first glance looks like a feast for someone like me that came from the limited WoW one. But shortly then you'll realize XIV's is also pretty limited too. The only thing it has in abundance is the skin/hair color palette and hairstyle options. Adding a couple of new faces and features would be nice, but only would be effective so far. The best course of action would be an overhaul to the character models and let us having sliders everywhere, something like GW2 presents already. This would proporcionate players to create really unique faces.

2) XIV's dye system is a bit weird. I'm fine with the number of dyes available, but the problem lies within the dye channels. With just 1 channel, you'll either find armor sets with just tiny parts of it that are dyeable, or on contrary, armors that are completely washed over the color, giving that gaudy photoshop-like color wash effect. XIV got hundreds of different armor sets, and it would be too taxing to "fix" them all with new dye channels, but this would be something the developers could work in future sets.


Now regarding just the RPG aspect of the game, I have some inputs on how it would make it more immersive:

1) XIV's capitals and the loading screens sort of set me off them being a really populated and busy location. I wonder if would be possible, at least there, to make it one huge zone without them, like they did with Kugane. The hingan capital might feel smaller than Eorzea's but it def. feels more alive and busy.

2) Squeenix investing a bigger budget to voice acting. I find really odd that even in the MSQ, some parts lack voice acting at all, just to a few scenes later bam... voice acting all of sudden happens. Also bring voice acting to the dungeon NPCs. Nothing worse than wanting to read a dialogue, but there is action happening at the same time, and in XIV you - need - to have your eyes glued on the encounters. The dreaded pre-HW MSQ times would be much less of a drag with voice acting.

3) Class/Job quests designed with a bit more thought. Honestly, post ARR, most of them are really bland because they seem to be designed without much complexity in mind. Give us job quests outside of just leveling and gaining new skills. Optional job quests with the content patches to develop the characters, to unlock a new emote, anything to make me feel more immersed in my job. And please, give voice acting to them, they are important, your job is how your character adventures in the world.

4) Introduce more Warriors of Light NPCs with powers equal of yours. Every plot seems to gravitate around yourself being the "only hope". While it's nice being the center of attention, it gets old a bit fast. How I wish they'd make Arenvald as powerful as yourself so it would be more of a equality relationship rather than a dependency one.