As a 60s era kid going to school, I can attest to the fact that schools established strict dress codes and behavioral standards.
The lack of parenting and the relaxation of established requirements have led to much of the antics being indulged in by high school kids to day. I concur with your comments about the ACLU and "supportive" parents. But, we wouldn't have this environment in schools today without the third component - a very willing and complicit NEA that is more wrapped up in the kids' "self-esteem" than in their ability to read, write, and perform simple mathematical computations.
I agree, except that I think the NEA is more sinister...