Imagine you're out looking for a job. You get some interviews. At each interview, they ask of you'll work for them if they give you a job offer. Why would you say no? You can only answer according to your current circumstances when the question was asked (the circumstances being that you're jobless).
So if interviewers ask you if you'll go there, are you only going to say yes at your 'top choice'? What happens if they reject you? Or you interview and your top choice isn't as great as you thought? Or what about all the financial aid info you don't know at the interview? It's different if you say 'yes' when you're already carrying an acceptance in your pocket, but when you're going through interviews without an MD acceptance at that point, I think you need to be as enthusiastic as possible about each opportunity, because each one may turn out to be your only one.
So if interviewers ask you if you'll go there, are you only going to say yes at your 'top choice'? What happens if they reject you? Or you interview and your top choice isn't as great as you thought? Or what about all the financial aid info you don't know at the interview? It's different if you say 'yes' when you're already carrying an acceptance in your pocket, but when you're going through interviews without an MD acceptance at that point, I think you need to be as enthusiastic as possible about each opportunity, because each one may turn out to be your only one.