What I'd love to see about the UI is a way to be able to customize it like relocating and rescaling the HP and resource bar, the Ability bars, Map and the chat. Also about the inventories and stashes to be able to choose whether to see them separated or all combined in one tab (like one huge bag). I think this would be a good idea as everyone would like to have what he sees on his monitor personalized. Whether it's because of his own taste or just because some of us are using bigger monitors than others.
I think that's a great idea hope the devs approve it too and to see it later in the game !