For me design and layout is a lot more important than size, though I in fact enjoy having a small house. I like having less to clean, less to heat, fewer places to lose things and a definite limit to the amount of (indoor) possesions I can amass. I easily feel overwhelmed by having too many things, and while I can dream of having spacious rooms for drying clothes, working on my bikes etc I know I'd also use them to store "things" rather than make an active decision on whether to keep them or not. Being able to store food and buy in bulk is a good point, though.
One of things I love most about going camping is having to pare down necessary items to a minimum.

Design: I want most space, air and sun in the living spaces, and that is what we have now. Tiny bedroom for the two of us, small bathroom, largish bedroom for our teenager, perfect for our needs.

I've read that it's easier to live greenly in urban surroundings too, but I'm sure that depends on a lot of factors.