You know, what I see as the problem here is that you people are clumping things together too much, and in doing so are letting the "bad" ruin the "good."
Just because all these things have "modern" slapped onto them doesn't mean they all have the same intent, purpose, effort, or idea behind them. Yes, a line across a piece of notebook paper has an element of BS to it, but does that mean you should hate on the whole genre because of that one group of silly work? No. What you're forgetting is that "modern art" is an extremely broad genre of art and contains a lot of different types. I don't think you should get your panties in a bunch over what a few artists do in Modern Art, because by shoving off that whole genre, you're also shoving off great artists like Vincent Van Gogh, Max Ernst, and Gustav Klimt.
And Re2Deemer, you forget one thing: The movement began in the 1860s, and it's changed as time moves on. It's a moldable genre, and the majority of things that fit into it also fit into other genres. Hell, entire other genres fit into modern art. Impressionism, Cubism, Surrealism, Pop Art, and tons of others are all considered "Modern Art."
I side with Occluded where the topic of interpretation of the more ambiguous works is involved.