Ben Golub's response to your post in the Caltech thread hits the nail on the head. Obviously your scores and grades make you competitive, but what sets you apart from the pool? What are you truly passionate about? Why are you a good match for MIT? What will you contribute to MIT's culture? What do you hope to get out of your education that only MIT (or Caltech or Chicago) can provide?
As Ben points out, the problem with lists of stats is that they're very one-dimensional. It's the human stuff that transcends that and makes you a strong applicant.