When I was young, they were cheap and cheerful and derided as "little boxes made of ticky-tacky".
Now that they're going for a million+, they are "mid century modern" and cool.
The design work of the Eamses is another case: https://www.vitra.com/en-me/magazine/details/eames-potato-ch..., it’s just a magnificent use of the material.
Even the original Case Study homes were intended to be affordable, not made as mansions: https://en.wikipedia.org/wiki/Case_Study_Houses (https://en.wikipedia.org/wiki/Bailey_House_(Los_Angeles)#Des...)
Needless to say, I think OP is just not well informed about design.
Just as it might have been hard to make an ornate street lamp, it’s also hard to make a clean modernist home. There are reasons (personal, practical, philosophical) to prefer one or the other for a given use, but the author isn’t seeing those nuances.
He actually also did mention that some things are simple yet still ugly.
The patterned china case though was precisely for arguing the more complex manufactured piece product being cheap AF.
I don’t think the author claimed it was bad to prefer simple, just that lots of public goods stuff are boring looking these days. I feel that way about a lot of concrete I see.
I would push back on “single most mainstream”. These decisions are not made by some voting mechanism. Many times it’s a local optima of loud complainers and opinionated decision makers. The most mainstream people actually can’t be bothered by most things, but would appreciate (IMHO) some intrigue from time to time.
Another related thing: HGTV disease. Where the house is all white everything…which I have a preference to now…but I do wonder if it’s just memetic influence of what people say looks nice.