Phi Beta Cons has several posts regarding the benefits of diversity (go to about 12:30 today -- 12/7 -- and scroll down.) Carol Iannone's point is particularly salient:

Diversity does not just mean racial and ethnic mixing. It is an ideology as well. Bringing diversity into every corner of the educational experience is the goal of the diversicrats, as Peter Wood has called them, so diversity can eat up every other educational value. Colleges spend money on vast campus-wide diversity "audits." The study of diversity, group differences, group inequalities, and the need for "social justice" (i.e. group equality), and so on become central, and multicultural and diversity courses have taken over many departments, addressing issues in a non-scholarly, ideological way. There also have to be sensitivity workshops, "difficult dialogues," and the like, conducted by students and consultants especially trained for this work. There are multicultural administrators and offices of multicultural affairs. One diversity manual recommends making sure that each group pursuing a project in a math class is racially and ethnically diverse. All of this takes away from the focus on education itself, on the transmission of knowledge, the study of the best that has been thought and said, the search for truth, and all those things that used to constitute an education.

But there's something more, I think, which is that the beneficiaries of diversity, to the extent there are any, are the majority group, not the minority. (Indeed, Rosenberg says in a recent post, it might harm them.)