My understanding of the not-so-big-house books is that the houses are still scratch-built, which, if you don't DIY, is even pricier than McMansions. When we were in (much) greater DC, custom-built, non-subdivision houses started at around 3000 sf, builders just didn't do smaller. In our town, building lots were a 6th of an acre, so if someone was building (not DIY), they needed 2 or more (adjacent) lots to do the job (as it was priced out to them, anyway). Crazy stuff.

Our house there was nearly perfect for us, 1400 sf, good for us + Thing 1 + guest room. Out here, similar price range gets <1000 sf, much trickier w/ the addition of Thing 2, so we went the other way, 1800 sf. House is old (>100 yrs, as before), so has the most economical use of space kind of built in anyway.

I guess that's been our solution, actually, buy old so the building dates back to when there was no choice but efficient use of space/material. Might not be great insulation-wise, but at least we're not using much in the way of new raw materials or land that hadn't already been developed for a long time.