> you end up with that much space in your walls anyway just because for material strength reasons you need wide walls.
For material strength, walls are fine with 2x4 framing. However, 2x4 framing is limited to R19. So this is actually not true. The reason builders went to 2x6 framing is entirely to allow for a larger insulated cavity.
> They still build the same roof pitches so rain runs off.
Roofs do not require the same pitch to dispel snow as they do to shed snow. Roof pitches are genuinely steeper in areas that see particularly high snow loads.
Builders have gone back to 2x4 in cold climates. They put 2 inches of foam outside. The wood of studs is r5 even though the insulation is r19, so the continuous foam is better.
And in warm climates there were going to 2x6 as well as air conditioning needed the r value.
For material strength, walls are fine with 2x4 framing. However, 2x4 framing is limited to R19. So this is actually not true. The reason builders went to 2x6 framing is entirely to allow for a larger insulated cavity.
> They still build the same roof pitches so rain runs off.
Roofs do not require the same pitch to dispel snow as they do to shed snow. Roof pitches are genuinely steeper in areas that see particularly high snow loads.