I'd like to see some form of custom housing in the game, not just here's a premade house/GH that you can decorate. I'm not against premade things by the devs because the devs should make things like that be able to look better, but I'd like something more than that.
Considering the success of the sims line of games, frankly I'd like to see something like that. You design it first in a designer tool. Then you get to work building it one piece at a time. Plus you could have crafters make things like furniture, art, and decorations for the house.
Maybe even allow a little space on the lot outside the house for adding a pond to fish in, a garden to grow stuff, a rock you can mine from, etc.