The funny thing is that I'll lay out my reasons for liking Julien Donkey-Boy and John will smite me for liking it for the wrong reasons. Let's see.
It's weird that I see it as a hopeful film. Not necessarily hopeful in the sense of its characters and their situations, but hopeful in that it's perhaps the most dirty and honest portrayal of mental illness I've ever seen in a film. Unlike his other films (and I've only seen Kids and Gummo), which seem to have a measure of detachment to them, JDB seems more personal. Indeed, he dedicates it to a relative of his with schizophrenia. You get the sense that as broken as they are, Korine loves these characters, even the nasty Dad. But he especially loves Julien. The scene where Julien's in the basement ranting into the mirror is particularly powerful. If Korine were just doing that for shock value, he wouldn't need to let it go on for so long. But he wants us to see Julien as he really is, apart from his family, apart from his world. Just him and the mirror and his illness, raw and laid bare. Not only does Korine honor Julien by showing him to us in all his broken glory, he also challenges the audience to dismiss their stereotypes of people with mental illness and to love them as they are. This is no Beautiful Mind. This is mud and pus and hose water and incest and the reality for so many people with mental illness. Why is this hopeful? Because we become aware. And awareness can lead to recognition and recognition to action. Maybe Korine didn't intend for all this with this film. But if he didn't consciously, then the film has taken on a life and message of his own. Either way, there are few directors who could so successfully portray mental illness without seeming preachy or sensational.