In the context of explaining why he didn’t go see the Iraq war movie, “Stop Loss,” Weekly Standard critic John Podheretz had this little rant about the the character arc, a feature of ‘Screenwriting 101’:
“It's only Screenwriting 101 over the past couple of decades. It's a perversion of the classic principle of fiction, which is that people are changed by experience. That doesn't mean people automatically grow from experience, or get better through experience, or become wiser, or become more enlightened. It just means that they are affected by what happens to them. In what passes for serious filmmaking in Hollywood, this change always occurs on a straight line. It is always for the better, and "better," in these instances, means that its lead character or characters start out as unthinking cogs in a status-quo machine and then, following a few dark lessons in the nature of evil (as represented by corporations or a Republican-led government), emerge from their cocoons to write angry and passionate blog items for the Huffington Post. Or the equivalent.”
Of course there have also been films showing someone going on a downward spiral--but they are very hard to sell, and in many hands that kind of journey is just as simplistic as the 'happily ever after' version.
Perhaps because of their longer history, its European countries that tend to produce films with a more sophisticated view of change. Maybe America's current events will eventually give it that greater perspective as well.