That's because he's trying to communicate with the idiots who voted for him.
BTW, we really don't know how intelligent 0bama is or isn't because unlike Bush, Gore, Clinton, McCain, and even Bidden, Obama has never released his grades in college or law school, his SAT scores, papers that he wrote, nothing. The only evidence of his intelligence comes from two, self-serving books that William Ayers ghost-wrote for 0bama at a time when 0bama was a nobody.
That's because he's trying to communicate with the idiots who voted for him.
His voters may certainly be idiots, but that's a speech habit that is completely involuntary. He is unaware he's doing it.