"I feel like a lot of the anti-AI people just... want there to be less beautiful art in the world"

I certainly don't want to speak for all "anti-AI people", but personally ...yeah.

Even before the generative AI boom, you could find an essentially limitless stream of artworks on the internet. If you exposed yourself to that for long enough, you'd eventually go numb to things just being beautiful for the sake of being beautiful.

Occasionally, you'd stumble over expressive art, which had a meaning beyond that, which conveyed an emotion, which was a labor of love and/or hatred.
Even before the generative AI boom, this expressive art was buried under heaps of profitable artworks, because artists were taking the second-best option for pursuing their passion.

So, while I would've preferred less profitable artworks and more expressive art, I was always perfectly fine with it, because I knew it was humans doing the necessary.

Now with generative AI, it's just yet another magnitude more artworks thrown on top, with even less meaning.
Where a missing finger might have been a powerful expression of the artist's struggles, now it's just an every-day-defect of the AI.

It just buries the expressive art even further, obstructs any meaningfulness and makes me even number to beauty. I absolutely do not care for a greater quantity of art. I want greater quality, and not in terms of beauty.