And to answer your somewhat rhetorical question, it started with political correctness and reached a fever pitch after 9/11.
I don't see how it had anything to do with 9/11 except the timing is similar.
Bottom line is that we're in at least the second generation of school kids brought up on PC bullshit. And a lot of the people running schools (and other institutions) are from the first generation that was immersed in it.