Interesting part near the end:
The mix of newly built homes has also changed, with large, expensive homes making up a greater share of home-building activity. Builders built 65,000 homes smaller than 1,400 square feet in 2020, compared with more than 400,000 such homes annually in the late 1970s, Freddie Mac said.
Households are getting smaller, birthrates are dropping and lots are smaller. IMHO there’s no reason builders should be abandoning 1,400 sq ft houses.