As far as I can see here there is two different views on jail-time here: one claims it is punishment, the other that it is about rehabilitation.
I can see why people want to lock those guys in for a long time in miserable conditions, but then they will com e out in the end as angry people ready to do whatever they did all over again.
On the other hand if they were sentenced to the same amount of time, but they had to serve that time with a good follow up-system, therapy, education and meaningful work, many of them would come out of it as different people that could actually contribute to society. Also if a person is becoming aware of how horrible his actions were, his own counciousness would be a life-long punishment.