People look at the cover when they buy a book! Shock!
Really, is anyone surprised? I wouldn't say that I'd buy a book solely on the aesthetic merits of its cover, but I've certainly noticed books because of their covers and it's sometimes pushed a borderline sale over the edge. Plus, when you go into a bookstore and are confronted with shelf after shelf of books, something has to grab your attention. Naturally, it's the cover.