Ahem... Butt slider!!

I kid, I kid. Not that I'm against it being an option.

If I had to pick something they aren't already planning to add, I suppose I wouldn't mind seeing them add Sephiroth to the game, as a character that randomly appears and kills characters named after those in Final Fantasy 7. There's just far too many Claude Stryfes and Sepirots. Plus it'd be funny. You know it would. Eventually they'd come to fear hearing the Sephiroth theme suddenly playing in the background.

Honestly, it seems like the features I really want so far are already in the works:

Vanity slots are a big one for me; I'll admit it, I'm vain.
I'm hoping they'll allow each equipment slot to show the equipped gear, vanity gear, or (at least for non-chest, non-leg slots) no gear.

I think most of the other things I would like, I'll probably be able to implement for myself when add-ons are allowed, assuming they aren't restricted to the point of being crippled.