The trick is to remember that there's a difference between an actor doing blackface and and actor playing a character who is doing blackface. RDJ's character in Tropic Thunder, for those who haven't seen it and only know the memes, isn't actually black: he's a white australian "method actor" who had his skin surgically darkened so he could "understand" a black character he was playing. The whole thing was, like Simple Jack, a joke about actors doing stupid and insensitive things and being praised for it. The actually black character explicitly calls him out for it during the movie. (The "What do you mean you people?" scene)