A couple of things
First, GW Bush lost the 2008 election as much as Obama won it. Once people got their 3rd quarter 401K results, John McCain was doomed. A lot of people who should have known better took the 2008 results to be the dawning of the Age of Aquarius. It is not impossible that Obama did also. Certainly, he acted as if he had more of a mandate than he did.
Second, the Democratic Party painted itself into a corner starting in 2000, assuming that the happiness of the Clinton 1990s would carry through. The leadership ignored the ill will that for some bad reasons and some good ones attached to Hillary Clinton. I suppose that she could have won in 2008; but she was selling inevitability, and once Obama put a crack in that belief, she could not get the nomination. In any case, she is not the politician her husband is. She has never needed to be.
Third, in my day one learned about the Electoral College in grade school. As best I can recall, there has very seldom been an elector who disregarded instructions--three or four since 1800.