I think it's an academic-specific derangement. They lose track of the difference between the symbol and the symbolized. So a wall-o-words is just as good as a gallery fulla paintings.
This is open data/metadata about art, not an attempt to digitize artworks. Also, the descriptions make it pretty clear that several of these institutions have made tens of thousands of digital images of artworks available.
Yes, we get that. Nevertheless an image or 2 would really tie it together.
As decoration, sure. I don't think it would really add anything to the information about the datasets on this page.