I haven't followed movies in a long while (almost 3 years now), but I do remember thinking these things a long time ago already.
A pertinent example would be one where there's no specific need for it and where it's overused. You've never seen movies where a black actor is obviously there to keep the cast's albedo "balanced"?
I'm not saying black culture automaticaly makes for bad movies but that it's abused just as that woman did in FX1's real estate video.
Norbit is supposed to be what it is, but in some movies where people are supposed to act normal you will see black people do the "black thing" like that woman FX1 dealt with did, and almost everytime it makes for a huge false note.
It would probably be just another cultural quirk among every other, except it's not just any benign quirk. It doesn't deserve a place in movies in spite of good acting anymore than falsehoods like the Evil Japanese cliche didn't deserve to take the place of truth in WWII news reports.
Personaly it's a borderline big deal.. I could easily just ignore it, but it's a damn shame and ought to disappear into history like slavery did. I know I get a little irritated anytime I can't get along with some people only because of it.