More character customization would be nice, but I understand it takes time for Blizzard to do that on an 8 year old engine (older, I think) where 10 million players will riot if the new models don't look the way they want (and new models are required to expand character customization). I think some games get carried away with it with brow, eyebrow, eye size, eye distance, eye height, nose width, nose bridge, nose width, cheekbone, upper lip, lower lip, ears, jaw line, chin, sliders. Nobody is looking at their character's face that much.
Also, look at WoW's requirements. Look at the newer MMOs. Blizz is really accessible and they try to keep that. Still, when the new models are released, I hope we see some more customization for them!
My input?
I'd like to see Blizzard approach, polish, and refine the concept of the Diplomacy system from Vanguard: Saga of Heroes. It was a genius idea to try and implement into an MMO and it's long overdue, but I didn't care for the card game style implementation so much. Still, it definitely added a mini game to spend time on and could actually have an impact on the game, so if Blizz could make it work, I'm sure they could do it with quality!