Anecdotally, we Americans are considerably less tolerant of violence that we were decades ago. What used to be a "pop in the nose" in now assault. What used to be a schoolyard scuffle is now a suspension, counseling, and possibly medication, possibly arrest.

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.