I'm sad that we're coming up towards 100 years on from Fallingwater being built, and yet the American preference for new houses of a similar price (after inflation) is the sort of awful stuff that shows up on mcmansionhell.com.
I suspect projects like fallingwater have siting considerations that wouldn't allow it to be built at all anywhere in the US... isn't it built basically on top of a WOTUS?
Larry Ellison owns a replica Japanese daimyo mansion in Woodside, two mansions on Bellevue Avenue in Newport, and 98% of the island of Lanai...but none of those structures there are (AFAIK) atop a permanent watercourse.
https://fallingwater.org/media-resources/fallingwater-facts/
Falling Water is his masterpiece. Most client homes were around 1,500sqft.
By the standards of the time, they were comfortable (if a bit lacking in closet space).
If you'd like, you can buy a modernized kit Usonian (inspired by the Jacobs I house) from Lindal here:
You will find new houses that small, but typically when it's extremely high value land, so typically infill. And then chances are it's a multi story house that fits the lot to the limit.
That said, the kit pictured will, if constructed, will have amenities & physical qualities that the similarly sized original Jacobs house has had to have retrofitted at great cost.
No idea what Wright would have thought about racial housing segregation, but it was certainly a knock-on effect of the preservationist cult he accidentally created.