Basing acceptance of URMs on socioeconomic status is certainly flawed, and its ok, I'll explain why.
First let me start off by saying that I'm not rich, but I'm certainly not poor. My mother is a pediatrician, my dad is a social worker, all of my mother's siblings are physicians, 30% of my church's members are physicians, others are lawyers, etc. Needless to say I didn't grow up in the ghetto. Now, according to your plan, despite the fact that I'm black, if another black person that grew up in the gettho with lower stats than me applied, he would get in over me. Now, technically that would make sense, but there is one thing that non-URMs probably don't understand.....MOST URMs THAT GROW UP IN GHETTOS OR SOCIOECONOMIC DEATH HOLES WILL NEVER GET OUT.
I work with kids in the projects all the time, and one thing that I've observed, and it has really broken my heart, is that most of the kids will never get the opportunity to make it. Most of their elders (and when I say elder, I mean that their grandma is like 30 years old) have only graduated from high school, therefore their parents cant' help them with their homework. The schools already suck, and if any kids in the area are just naturally smart (without some intervention) they will probably end up running illegal operations in the projects rather than being the footmen. For many of the kids, the only way out is through sports are music, and we all know how reliable that is. All of their role models are athletes, rappers, or local drug dealers who seem to have it all. They don't have many intellectual, academic role models to emulate, especially the black males.
So you say that medical schools should just take into consideration the socioeconomic status of the applicant, and figure that that will denote where they will return to. This is flawed first because of the black URMs that apply, probably like 1% of them actually came from ghettos or poor socioeconomic backgrounds. Most of the URMs that apply come from families that have gotten out of these poor areas to make a better life for their families. And believe it or not, it is people like this (like me) who desire to go into poor areas that they didn't grow up in, and give back. We want to serve as role models to the people in that community, so more will have a desire to stay in school, etc. So yeah, stop with the fairy tale stuff...blacks will want to treat blacks, and the majority of blacks are below the poverty line. Hispanics will want to treat their own, and the majority of hispanics are below the poverty line. Asians will want to treat those in their same class, which include thosewell above the poverty line, and so on and so on.