First things first the lighting is not that impressive, any chance on making it where it looks like real lighting? I know it's just an effect but it still would be nice to have. Also the ability to manipulate the light in a manner of how you want the light to spread, and where shadows come into play.
That's my first suggestion, next it would be nice to have objects with slider bars. Let me explain, say you wanna make a certain object and you simply can't achieve a curve or bump or whatever you need. Having sliders in the objects would be nice as you could choose what area of the object you needed to edit and could adjust for height, length, width of the area. It would greatly improve how authentic something could look and would allow for more unique looking objects.
Another nice thing I would like to see in the game would be the ability to add certain properties you like to vote on to a kind've property list. In the list would be shortcut windows to those peoples voting booths, where you wouldn't need to needlessly meander through either catching a teleport or flying over to the persons home. To me you can keep good friends whom you haven't seen or spoken to in a while in-game in touch.
Last I'd like to see an ability to expand on the texture stretcher. Within it would be the ability to add sheen or a shiny surface to objects. This would probably work best on colored objects better than on textured objects. But this way you can make, say a car for example, or a machine and not have a simple dull look. Testures can add shine I admit but it's just a flat shine that doesen't do anything really IMHO.
Those are things I'd like to see added to the game, if they can't be done, then oh swell, I was just trying to think creatively.