But they stayed for the whole thing right? Most people walk out of a movie they hate that much. I remember my friend and I were the only ones left in Down To Earth, and no matter how bad a movie is I have never seen that happen before. Quite a few people walked out of Crash when I saw it, though it was hardly a secret what kind of movie that was... the rating alone should have clued people in.
Some people just don't want to invest their imagination in things anymore. And I think that TBWP is a horror film for those with vivid imaginations, a thinking-persons horror film, so to speak.