I wonder though, can we really use racial diversity as a proxy for diversity of thought? I mean, clearly, an asian person will necessarily have had a different upbringing than a caucasian, but the same is true of a poor southern caucasian as compared to a rich boarding school-educated caucasian, or asians brought up in california versus same in new york. While the benefits of diversity for its own sake are debatable, if diversity as such is a goal, then shouldn't one be focused on the degree of diversity? Should there be a diversity quotient, where american asians get, say, 2 points while asian asians get 4? What about a caucasian who was raised in asia? is he caucasian, or is he even more diverse than than the asian-born asians? more important, do we create some artificial 'center' (white male, middle class, ivy-league education (for UE b-schools)) or do we only go so far as to ensure that everyone is different?
I guess what i'm trying to say is that, while race on it's own can serve as a broad indicator of diversity of thought, it isn't going to go as far as even a simple examination of experiences will. A recruiter is not going to take a longer look at you if you are of middle-eastern descent but don't have the correct experiences/skills (or at least, I hope she won't). If the company wants a different type of thought, they probably shouldn't stump for people who have the same degrees as the people already working for them--McKinsey would be much better served by a caucasian from SIU-Carbondale than an african-american from Princeton. Race alone just isn't enough.
That said, the schools do care (probably for their admissions brochures) about racial diversity, but it seems that, outside of the sort of affirmative action-minded program that they might have in mind, that factor itself is of little value. Plus, if helping underrepresented minorities is the goal, a business school is probably the wrong place to do it, simply because one has to have already cleared several hurdles (like good college and good work experience) to get in, and those hurdles all depend on previous hurdles (like a good high school). I'll bet you that most of the UMs getting into harvard have the same yale degree as the other admits.