I'm always a silver lining, glass half-full kinda guy.
(Although I'm always wary the half full glass might be piss...)
I do think that the Manson murders did help bring the hippy phase of the counterculture to an end. And that's not a bad thing. I think most here know the truth that it definitely had its dark underside, full of class-envy and hatred for the "squares". Much like the rhetoric we've heard from the Occupy movement and Antifa. It was not all free love and pot/LSD, and Woodstock.
While it's certainly still execrable for any number of reasons, it seems that the cultural Zeitgeist for the "cool kids" started shifting to the Disco era. Still hedonistic, but much more materialistic, and lacking in that drive to "change society" for the most part.