hippies are mocked simply b/c they're an easy target, plain and simple. i've never had a problem with them, despite their undying support of horrendous jam bands, haha..
the one thing i'll give the hippies props for was the simple fact that they were one of the first in the very conservative 60s decade to stand up and disrupt the status quo, to say "this way of life isn't for me and you're going to hear about it". the hippie movement started off with strong intentions until its natural downfall. or as that one Family Guy episode put it: "we lost the values but kept the weed."