I'm more surprised there hasn't been a more thoroughly featured, higher budget Minecraft-sort of game by a respected studio.
The whole idea is gold, but I think the 'depth' of the game is really quite shallow when it comes down to it. Yes, some people get very creative and create lots of 'kinda' useful redstone contraptions and whatnot, but I feel its really only scratched the surface of the kind of things possible.
I do think a better looking Minecraft clone would be nice, too. Perhaps still retain some of the blocky, Lego-like aesthetic for practical purposes, but just like with legos, some more shapes would be nice and useful. I'd also like a much better draw distance. Its a shame to have such a nice, huge world just get 'cut off'. Ruins a bit of the immersion for me sometimes, especially when in higher elevations looking around to the horizon.
Basically, they need to create 'Lego: The Game'. They could expand it like they do with The Sims, having Pirate packs, and Space packs and whatever else. They seem to already have licensing deals for things like Lord of the Rings and Star Wars and stuff, so thats all something that could be included as well.