I'm on a mailing list for bookstore folk and every week they ask an author or book person several questions about their reading habits. One of these is to name a book they bought for the cover and the vast majority of answers are "none". This seems strange, so much in fact that I think most of them are lying. The feeling apparently is that if the pursuit of literature is a lofty activity then it shouldn't be sullied by anything as crass as packaging. The thing is, though, that true bibliophiles (admittedly not always the same thing as literature-seekers) love the physical object of a book, cover and all. That's why I can't really believe that most people actually in this business, actually writing, don't care about covers.
Or maybe it's just because I've always been drawn to the covers. In high school I collected anything with a Frazetta cover and though his work now seems too static and too cramped I still like the sense of forbidding and mystery that his best work evokes, helped by a fairly imaginative use of color (imaginative for pb fantasy illustration, not by art world standards). Since then I haven't been able to resist at times some of those remarkable 50s/60s paperback covers (though I never go to collector prices) or well-done trade dress such as NYRB Classics or occasionally just a striking cover. I'm certainly not the only person to have an almost-Pavlovian response to orange Penguin spines. In one sense, yeah the covers and paper and type are the window-dressing but really not that much. They do have real effects on the way we read the book even if we're mentally trying to create an ideal that's independent of that.