You have valid points. A good example, here in Stockholm, is Gamla Stan (Old City) beautiful buildings (https://en.wikipedia.org/wiki/Gamla_stan) and the "Norrmalmsregleringen" (https://en.wikipedia.org/wiki/Redevelopment_of_Norrmalm) with an example https://www.reddit.com/r/europe/comments/8hlk9r/the_grand_h%... . The ornamentation was removed to "sanitize" the building.

It similar to clothes fashion. There is nothing stopping us to create 1700s style clothes (https://en.wikipedia.org/wiki/1700%E2%80%9350_in_Western_fas...). But these clothes are not fashionable anymore. Nothing stops Europeans to dress in traditional Korean clothes (https://en.wikipedia.org/wiki/Hanbok) but it is not happening.

Brutalism is a style, it is a choice (https://en.wikipedia.org/wiki/Brutalist_architecture).

Official buildings are way uglier nowadays than they used to be. It is probably related to cost and speed. And it is probably a good decision. But that does not mean that the buildings are beautiful.