> Why do communists build brutalist buildings?

Typically because they face a huge population move from the countryside to the city areas, and thus have to build as fast as can be and on a budget, which leads to what you can see there.

You can observe a similar pattern in many countries, e.g. here[0] in France, in the Lyon suburbs.

[0] https://france3-regions.francetvinfo.fr/image/boW0onRHUjdzzl...

Because there's overlap between what brutalism is about and what communism is about, an exposure of the material and structure to the outside, a rejection of nostalgia and traditionalism, etc. Of course this isn't exclusive to Communism but also quite popular in the US, as the other big cultural center of modernization in the 20th century.

This has nothing to do with abandonment of aesthetics though, as Brutalism is a very explicit aesthetic and architectural movement. We did indeed abandon aesthetics but the product of this is the non-offensive, utilitarian, convenient Starbucks store, the Ikea furniture and so on, not Brutalism.

Brutalism and communism are what happens when people pretend that human nature doesn’t exist.