There's no conspiracy.
I believe the main reason was a general feeling in the air that if America elects this guy, we'll get to bury old racial tensions, show ourselves to be enlightened and be welcomed back into the good graces of the world community once again. So let's not ask any uncomfortable questions that might produce uncomfortable answers and let's not allow anyone else to ask uncomfortable questions that might produce uncomfortable answers. Let's instead just rally behind this guy. That's why Hillary didn't ask questions, McCain didn't ask questions, the media and on and on. People didn't want to know anything about this guy. They just wanted for him to be president.
White guilt elected Obama.