Why? Simple. Because General Elections are run like Primaries. They are NOT run like Caucases.
Explanation on the flip...
Witness Hillary's strong showing among Primary voters. She wins primaries, Obama wins caucases.
Translation: People SAY they want a black candidate but in the privacy of the voting booth, they vote otherwise.
Hence... Obama will lose.
I consider this to be a major flaw, among many, in the Democratic Nomination system. The system we have now is nothing more than a popularity contest that encourages fanatics and He Who Shouts Loudest. We are not getting the best candidate out there. We are getting the Flavor of the Month.
Vote for Hillary Clinton if you want change. Obama will never win against McCain.