Dan,

Somehow I have some trouble imagining some of today's builder spec houses as
ever having design significance.  Just the fact that a design is a
vernacular interpretation, or even decent mass production of high style
architecture doesn't mean it is insignificant.  Know you appreciate that
from the "material culture/social history" slant of your post.  In most
cases my personal preference runs to the simplified vernacular versions.
Much like the American versions of high style 18th Century English
furniture.

Tom