Haha, Queentess, I figured that was it.
As for why it was "never going to be taught", I have to think it's just plain not old enough or "classic" enough to make the cut on the standardized tests that are oh-so-important these days. Certainly I was never taught Vonnegut in high school; was anyone else in this thread? But, yeah, removing it from the library entirely is a bad move.
Twenty Boy Summer. Heh.