Ideally people would have a variety of options for size and style based on what they like and can afford rather than being forced into your personal preferences. There are more important factors than energy efficiency for most buyers. While I don't have a McMansion myself, they are actually quite livable for the target market of upper-middle class suburban nuclear families with children. The major homebuilders literally hire sociologists to do field research on such families and then design house plans to fit their lifestyle.

Architects don’t design McMansions. The lack of an architect is actually how they are produced. Less than 10% of housing in the US was designed by an architect.

> I think ideally we would all live in modest, reasonably sized simple rectangular houses that are built to last, to be energy efficient, and which achieve low cost through standard designs.

In an ideal world yes, in the real world you'll get run out of town being called a "communist", or no one will buy the houses because actually built-to-last homes are waaay more expensive than the cheap drywall and wood stuff that one sees go up in the air with every tornado video.