Is because they lack the intelligence to comprehend the sub text. His he is a true genius and the best film maker since Howard Hughes. Don't get mad if you hate his films, some people just aren't meant to be smart.
I really enjoyed 'The Sixth Sense', 'Signs', and even 'Unbreakable' (my personal favorite). But recently, he's just been making terrible decisions in the directing process. I don't know what happened; it's a conspiracy, I say.