Bullshit.
Adults have always said that the young generation is degenerate, violent and generally inferior. To that of the adult population. Teenage crime has not been as low as it is now since the early 1960s, but a few tragic crimes have caused a false sense of increased crime. During the Civil War, newspapers routinely printed about young gangs prowling the cities with clubs and chains.
Most mosh pits, which by the way have been around since the late 70s, are not violent . Despite what many people think, they are not fighting. I mosh all the time, and have never been hurt more than a slight bruise, and have never hurt anyone else. I bring my 15 year old sister to these things, and she has never been hurt at all. I live on the East Coast, which has faster mosh pits, but still will forcibly eject someone throwing punches and part if someone falls or needs to tie a shoe. I once saw a crowd of 200 part so someone could find a contact during a hard, fast song. Those who show up for a fight won't last long, and those who came to dance will last all night. The crowd surges with you and even as you bump into people, you feel the music. Its truer dance than simply performing steps.
America hasn't reached its violence peak. That'd either be during the Indian Wars, the Civil War, the 60s, or early pioneer days. Capitalism has been pushed since the advent of Calvinism and other protestant faiths. Also that high amount prisoners is a problem. But a majority of them are there because of drugs, either using, selling or commiting crimes because of. These aren't aggressive crimes, or even most of the time violent crime.
Those who say money is the root of all evil have always had it.
Update-flamingweasel is right. I was quoting violent crime statistics.