If its real, you think to yourself, 'wow, that's an incredible story. I can't believe that happened.' If its a fake story sold as real, then its just a montage of cliches and sappy story lines meant to manipulate the audience into having an emotional response based on their belief that its true.
One thing that is sort of bothersome is that the movie deliberately lied about the racial stuff just to 1) make America seem really backward, more than it actually was at the time and 2) manipulate Americans sensitivity toward race to sell movie tickets (I get it, a lot of movies have done this, but completely making up widespread racial bigotry in a town and claiming it really happened just to make your audience shed some tears is kind of messed up).