Bill Clinton was president when I first started paying attention to politics, when I was an adolescent. I saw how he drove them absolutely crazy on a personal level. Obama didn't drive them crazy, he was just Black. They would have treated any Black Democrat who became president the same way, which means it wasn't about him.
All of that is true, but it doesn't change the fact that they still hated Obama more - even if it was just petty racism.
They basically hate the idea of a black president more than they hated Clinton.