I don't think that's unique to AI --- many sites always had the same bland style, especially corporate ones, and I remember all the complaints about bootstrap.css when that was the trend many years ago.

I witness a large amount of AI generated pages at work and in the wild. Creative control belongs to the human because without it you get a scientifically accurate model without the stargazing factor.

I have built a few better sites after AI generates the shell. The colors and styling need about a dozen human interactions to get something passable as human created.