I know you'll duck these (and I would hate to distract you from whatever feast you're putting together for this evening), but:
If not for affirmative action, then do you think there would be people of color in any American institutions of power? Yes. I think people of color are perfectly capable of succeeding on their own merits.
Is diversity important in American institutions of power? Diversity of thought is most important, yes. Ten people who look different but think identically don't yield the desired fruits of diversity.
Do you think that more diverse institutions would be better fit to solve the problems that you so often (de)rail against on every Tunnels? I suppose it depends on which institution you are referring to, and what type of diversity. Assuming you're just referring to the diversity of the color of people's skin, I don't see how that matters nearly as much as the choices people make in their lives. (Sidebar: That's the good news. Isn't it?). Would you rather be born to a family of college educated involved parents who happen to be black or be born an undiscovered Honey Boo-Boo in a single wide to an tenth grade educated single mother somewhere on the Wrangor Riviera who happened to be white? I think there is more to one's circumstance than pigment.
I don't know the answers, but I do that the free market, when left on its own, tends to both practice and reinforce racial discrimination because of the systematic devaluation of people of colors' lives in this country.