Few would argue diversity isn't important. It is not terribly well established that cutting along racial boundaries is the correct way to establish diversity.

Shouldn't we give affirmative-action style bonuses to conservatives, since they are grossly underrepresented on campus? After all, everyone ought to agree that students should be exposed to such common viewpoints; whether you think that's because student education is being limited for lack of exposure to their different viewpoints or whether you consider the ideas so transparently false that students can be safely exposed to the ideas so that they can be shown how transparently false they are, using the same racial-diversity logic says that we ought to be giving huge conservative bonuses for admission and tenure positions. What advantage is "diversity" if the result is merely a rainbow of people all identically singing the praises of the white-liberal-sourced diversity ideals?

The affirmative action for diversity logic does not trivially obviously cover skin color issues. It argues for ideological diversity, then slides in race as a proxy for ideology when you aren't looking. I consider the entire race-based affirmative action line of logic pretty offensively racist if you actually analyze it.

(I'm not arguing in favor of conservative affirmative action bonuses. Look more closely if you think I just did.)