I hear what you are saying but disagree to a point. How many of these people getting arrested for the serious crimes have pre existing arrests / convictions for minor crimes? Once you have a couple of minor arrests and you are in the system, finding a career and advancing yourself becomes increasingly difficult. I would make an uneducated assumption that if they had not gotten the minor infractions and had a future perhaps the major infractions would not have happened. With that said there are always going to be bad people that require police intervention. Further adding to this if you grow up in an environment where there is a high criminal element you may be more predisposed to it, starting with minor infractions like marijuana use and then you are arrested and the self fulfilling prophecy repeats.

Massively increased policing has created the environment in which many of these people are born and turn to crime. If you are constantly treated like a criminal, you may come to think of yourself as one.