Yeah, most movies don't really capture the situation of the mentally disabled do they? I have worked with them a lot, but hollywood does not really understand their struggle, or chooses not to show it. Its harder to make a good movie about a person spending their lives struggling to be normal like everybody else, when you could make a movie with a guy like Forrest Gump doing heroism out of impairment.
Agree completely.
I think it must be, the actor's ego takes over. To do it right, an actor's persona would have to be completely subsumed by the character's real life and emotions, which would help lead to a dignified portrayal.