While on the surface it sounds interesting, I'm not entirely convinced it's a good idea to allow villages to generate in every biome. Maybe limit this suggestion to just the snow biome, as that's the only one that has nothing overly unique to it. Houses can be made from spruce and snow blocks.
And just forget about Extreme hills! Those villages would be Messed Up! I mean, you've seen villages that generate on the edges of ravines and small hills in plains, right? Multiply that weirdness ten-fold.
We have enough villages on average as is...and sometimes even too many. Can you imagine how many village there'd be if they appeared in pretty much every biome? It would become redundantly annoying very fast. Also, I've seen extreme hill and jungle villages. They look really bad and stupid.
this might sound like something that could happen on the PC since the game is technically infinite and villages are very spread out and rare to find but because you are extremely limited on consoles and tablets I don't think it would happen.
I thought I read a rumor that Mojang were going to add snow villages in 1.9... but I could be waay off base.
I think it would be neat if they did expand the types of villages to match some different biomes. I think this could be done without increasing the frequency of village generation. I agree that game-generated villages don't come out right in hilly biomes, so I think I would limit the idea to two biomes: tundra and savannah. Yes, I know that villages do generate in savannah biomes now, but I'm thinking they could be styled a little differently than the plains ones.