It's just the way things work out. WashU does have a reputation of putting more emphasis on the numbers than anything else. I'm not going to lie and say that it's not true, but it is. That's not to say they don't care about anything else, because they do. They tend to interview the students with high numbers and then from there pick the well-rounded students. If you look at my class, you'd never think that we were all chosen for our numbers because we weren't, it just helped us along the way.
That's not to say that they won't accept people with lower numbers, I think it just tends to be harder here because I believe they use it as a screening tool of sorts. They don't complete rule out people for lower numbers, but they'll need to have something extra special to boost the application up.
As far as picking WashU over other top schools, there are plenty of reasons - money, location (weird, I know, but some people like the Midwest), research, fit, etc. There are plenty of people in my class who turned down offers from school ranked higher (Harvard, Penn, and Hopkins), myself included. I personally fell in love with the people at WashU and couldn't imagine going anywhere else. Those three schools aren't the end all be all of good medical education, and while WashU is trapped in the middle of the country, it's still a great place to go to school.
