As much as I hate to bring "the children" into any debate, here goes nothing. Imagine what's going on inside the brains of black (and white) kids, who are constantly bombarded with fictionalized black people who don't fit in, will never fit in, and the mere thought of them having positions of authority or holding any responsibility is presumed to be a joke with no questions asked. How can anyone legitimately bring up the thought of a black president, when the idea is still far more likely to be made into a Hollywood comedy starring Martin Lawrence?
Even a cartoon like Shrek follows the same old pattern, with Eddie Murphy as the voice of the jive-talking "donkey with attitude". Sure, Murphy was funny. But the movie still relies on audiences to get off on seeing the juxtaposition between the voice of the ghetto and the image of an animated Donkey in the Land of Make-Believe.
I might be crazy, but I actually think that the voice of an educated black man with proper diction can be entertaining, too. I don't need every white actor I see to talk like Biff the Hollywoodized private-school WASP, nor do I demand that the Asian ones sound like Pat Morita telling me to wax on, wax off. I actually think that people don't need to be forever tied to their "roots". They can actually be unique American men and women of independent character.
But of course, having such a character in the movies would require that Hollywood go to the trouble of creating some.