I have a friend of mine who did an MBA during a year off. I don't think she saw it as a huge benefit when applying for residency, although I doubt anyone was "turned off" by it. There's this whole image that docs are "allergic to money", yet the fact is to maintain a decent practice that has longevity, you need to be financially adept.
Overall, I agree with the above. Your app needs to tell a story. If your MBA contributes to the message you wish to convey to the committee about you (very innovation/business minded, belief in appropriate practice structure, etc..), then awesome. If it looks like you just threw random stuff into your shopping cart to make it seem full...just like everything else, it probably doesn't help as much.