I'd love to be able to change my character's height with the height brackets suggested by the 5e race blocks. though that comes with saying I'd appreciate the ability to customise our charcters beyond face/hair/eyes AT ALL.... which we can't. We have zero actual body customisation in this game, whatsoever.
Specifically, that would also mean that they'd have to adjust halflings to actually be, you know, halfling height... which they are not, at the moment; they're far too tall.