Barack Obama polarizes America because of what he is.
He is incompetent, without any justification, and that's what turns people off. He's an intelligent person, who went to Yale and seems to have respectable moral discipline, yet he fails quite spectacularly to wrangle Congress or achieve anything, without rampant deficit spending.
This is the story of Barack Obama, they guy who looks good on paper, but who gives in to his self-indulgent political impulses to the detriment of the nation.
I understand why people defend him, but he is easily the worst post-WWII president.