I fully see where you are coming from. However, I have to fully agree with DocSherman's comment that the point is the experience and to hopefully build strong relationships and connections with the PHSU faculty and build your application to show you are capable, ALONG with everything else. Not a get-in-free card. However, I understand the main campus' ratio is bigger, understandably, as they have a larger program and a program that's been around for much longer. I want to say the STL on-site MSMS has been around for just a few years before the MD expansion. I've also met MSMS students who want to do other health professions as well and not medicine, which is totally cool too. So not everyone is automatically turning around and applying to the MD program.
But being frank, you have to earn your place in medical school. If you don't have sufficient and relevant clinical experience to show your motivation to be a doctor and understand the work and responsibilities you'll one day have, you should not be applying. If you can't coherently demonstrate why you want to be a doctor, you should not be applying. If you don't have volunteer hours to show you are a compassionate person and want to help your community, you should not be applying. If you don't have extracurricular involvement showing you are a sociable person, you should not be applying.
They say your application gets you the interview, then the interview is what gets you the acceptance. If you have a "good-on-paper" application but totally mess up your interview, you can very well not get in no matter how good you look on paper.
Perfect and near-perfect MCAT scorers get rejected all the time because of lacking components of their app or their interview. Just because you got an "MSMS at PHSU," it does not mean you're above that same scrutiny.