10. Unbelievable Heroes
Did you ever watch
Halloween and wonder how a wimp like Laurie Strode managed to go from hair-twirling social outcast to badass-Michael-Myers-fighter in a single night? I think many of us watch these "super" hero movies with a little bit of subconscious disbelief. The hero of a modern horror movie almost invariably becomes something he / she is not. Hitchcock heroes tend to be the "everyman" type of hero. There's never really a scene in one of his movies where the protagonist is ridiculously larger than life. That's a big part of what adds to the suspense of his films - if it happened to you, you would probably behave in much the same manner as the hero.
That's about it for me. I'm sure there are a few other reasons that Hitchcock would turn over in his grave at modern horror, but I'm spent. Any other thoughts out there?