Also, are you 100% certain that this doesn't reflect a change in what people are charged with, rather than their actual behavior? Have you any experience with prosecutorial discretion and how that affects what people are charged with, and hence, the "crime rate."
Do you have any evidence to suggest the definition of violent crime has changed at all? I'd be very curious if that were the case. In the absence of evidence, though, I'll continue going with what I understand to be the generally-accepted theory that crime rose dramatically throughout the 1970s and 1980s.
Whether that has any bearing whatsoever on crime stats, I have no idea. It could even be a response to crime going down, or completely unrelated.
It would be really interesting to try to figure it out.