Robert Tagorda has a first-person account of the myriad absurdities of the diversity rationale for affirmative action.

I disagree with some of what Orlando Patterson wrote in his Sunday New York Times essay, but he does an excellent job of spelling out the problems with the emphasis on diversity:

while diversity is a goal that deserves to be pursued in its own right, it was a major strategic error for African-American leaders to have advocated it as the main justification for affirmative action. In doing so, they greatly expanded the number of groups entitled to preferences — including millions of immigrants whose claims on the nation pale in comparison to those who have been historically discriminated against. Such a development understandably alarmed many whites who were otherwise prepared to turn a pragmatic blind eye to their principled concerns about affirmative action.

Using diversity as a rationale for affirmative action also distorts the aims of affirmative action. The original, morally incontestable goal of the policy was the integration of African-Americans in all important areas of the public and private sectors from which they had been historically excluded. But if diversity is the goal, the purpose of affirmative action shifts from improving the condition of blacks to transforming America into a multicultural society. Thus the pursuit of inclusion is replaced by the celebration of separate identities....

The gravest danger, however, and what perhaps alarms the majority most, is the tendency to view affirmative action as a permanent program for preferred minorities and, simultaneously, the refusal even to consider it a topic for public discourse. Indeed, among the black middle class, especially on the nation's campuses, blind support for affirmative action has become an essential signal of ethnic solidarity and commitment.

Then there's Dahlia Lithwick's logical demolition of O'Connor's majority opinion. It's no use excerpting it -- just read the whole thing.