Just took a look and there are some abstract wallpapers, which relativates my rant a bit. I still find the sheer mass of forests, flowers and seasides even coming from Microsoft plain boring. But that is my taste apparently. I think what lacks is good abstract wallpapers fitting dark mode in decent resulutions up to UHD.
There are a couple artists still making abstracts UHD --AND 4K
The landscapes are starting to flood the file a bit I agree