Plus, we've had black candidates before like Jesse Jackson, Al Sharpton, and Carol Mosely Braun, who got nowhere, so obviously there's more to Obama's candidacy than just being a black.
They did not have the support of a desperate party behind them grasping for any chance of increasing their odds of wining. The fact is no matter who they chose they were going to run into the facts that I already pointed out. Why do you think their last 2 candidates to choose between were a black guy and a woman? It wasnt because they were most qualified, it was because they were trying to figure out who would get the most votes. Unfortunately they realized that women are more likely to vote for whoever they think will do best, regardless of gender and that blacks will vote for a black because... he's black.