Walkability demands density, and density intrinsically is encouraged by smaller units. Now, obviously the economic factor you describe can exacerbate this, but fundamentally dense walkable neighborhoods can't have the kind of sprawly mcmansions some people have grown comfortable with in suburbia.
I live in exactly that kind of pre-war streetcar suburb and yes, I've heard suburbanites complain that the houses in these neighborhoods are too small and narrow and lack attached garages. So yes, even the moderate walkability created by streetcar suburbs is still requires a shift to noticeably smaller homes for many North Americans acclimatized to sprawl.
