Why is the idea of rehabilitation a nice 'secondary goal' to the primary goal of stopping the person from committing crimes? By forcibly incarcerating someone, you accept responsibility for what happens to them during their incarceration as well as their attitude afterwards. If you fail to even consider providing incentives or starting any kind of positive feedback loops for good behaviors for those you've restrained, then you fail to live up to your goal of stopping the person from committing crimes. Oh, you get a few months or years respite from them while they're in jail, but unless you plan to keep them locked up for even the pettiest of "uncomfortable crimes" such as burglary, then they WILL be released in time.
Tailoring the punishments to assistance to not commit crimes, even if that assistance means a support group for someone who's lonely and steals something to get attention instead of jail, you gain real improvements in peoples lives. It is called the 'Department of Corrections' for a reason. Perhaps it's time we started correcting the issue instead of just shutting them away.