Oh I find plenty to praise in individual dark academia. The Secret History is, after all, a story about academic elitism and the dangers of it. But for people who use dark academia (or light academia, or its general spinoffs) to represent a general love of learning, I feel they'd be better served by focusing on a more democratized and accessible form of learning than just trying to mimic the aesthetics of wealth and exclusivity that dark academia is founded on.
As for it's hard to turn into an aesthetic, libraries do have an aesthetic. It's bright and colorful kid's sections, bookmarks, funny signs, armchairs by the windows, community art pieces, study rooms full of laughter, book displays, rainbows of books, the occasional cat.