I don't know if that would have helped. I figured out the twist long before its revelation, and I think the movie would have made even less sense without some

I don't know if that would have helped. I figured out the twist long before its revelation, and I think the movie would have made even less sense without some kind of explanation of the characters' strange behaviour. I came out of it thinking "I guess some names can get anything funded", since it seemed like an obviously bad story, but with more hindsight "obviously bad story" is not a problem for a film project if it makes money (just a problem for the audience), and in 2004 Shyamalan's name on a movie was guaranteed to make money, so the investors had no need to care about story.