The exceptions though prove there is a problem with the system. You ask what would be wrong with giving preference to the black candidate; well, I think that constitutes racism. Give it to the candidate most deserving. I don't think race should be a tiebreaker, nor a bonus system. Obviously we all want to get to a point where everyone has a good chance of success, no matter race or socioeconomic status. But I feel for many reasons that AA hurts not only qualified people who are bypassed, but unqualified people who are selected.
You state anecdotal evidence, and it's certainly compelling. That needs to stop, but I don't believe AA is the best way to go about it.