Actually, I suspect that tall people do have higher rates of acceptance than short people, assuming equivalent grades, MCAT, and EC's. I also suspect that people who are very physically attractive have higher rates of acceptance than unattractive folks who have a comparable academic and extracurricular record. Of course that is not fair, but it probably is true.
Have you noticed that U.S. Presidents tend to be taller than 6 foot - there is a sociological reason for this. Why do you think that Dennis Kucinich's presidential campaign is going nowhere, aside from the fact that he publicly affirmed his belief in UFO's recently. As I recall, Kucinich is about 5'6" and when he is in a group debate on television, all of the other candidates are looking down on him physically. So nobody takes him seriously. Of course, Hillary is not six foot, but the ladies are held to a different standard. She just has to prove that she is tough enough to order the fighter jets into the air and bombs away when the circumstances demand it. Now, Golda Meir, the former prime minister of Israel, that was one tough grandmother.