My criticism is largely limited to the realms of Fantasy and Sci-Fi--I can't speak as much for the other genres. But as someone whose consumption of decades-old sci-fi and fantasy novels has skyrocketed since getting an e-reader, I am constantly struck by how bland the cover of the e-books versions are compared to their 60s/70s/80s tradeback counterparts.
Examples
I could go on, those happen to just be three I read in recent memory. I don't know if the "minimalism" aesthetic took over all things, or if publishers re-releasing older novels decided they didn't want to spend the extra capital required to license those old covers and/or commission new ones. But it's sad. Older sci-fi covers felt like they were stretching the limits of imagination, and modern ones just feel...bland.