Your OP is a fairly classic philosophy question, one you'd probaby reach quickly in any basic course in philosophy. What is the value of punishment? The value to the punished, the value to the punisher, and the value to other actors (society, culture, relatives, etc.). The thing is that it isn't clear that punishment has much value at all. Any value extracted tends to be founded upon the ASSUMPTION that it has some preventative or "restorative" value (i.e. it will teach a lesson/change future behavior). The problem is that scientifically, most of the justifications can't be supported. Punishment more than likely does not make people conform in the future, but makes them better at not getting caught.
And the concept of retribution for the victims/society/relatives doesn't hold much water either. There is little if any tangible use of punishment to the victim. They almost never feel "safer" because of the punishment. It rarely makes them feel "better", they more often than not still feel the victim despite the punishment.
Restititution can often be demonstrated to be useful. It both provides a "natural" consequence to behaviors, and compensates a victim in some sense to "undo" or "correct" their consequences. However, certain things can't be "compensated". A lost life is difficult to compensate. A fatherless child or a childless father cannot be compensated. At that point, punishment merely takes from the perpetrator, but does not serve the victim.
Of course incarceration has a purpose beyond punishment. It can serve to protect society from future acts of the individual. However, although we incarcerate people, we tend to do it in a way which is also intended to "punish" and it hasn't shown to be useful to anyone, including the punished. And in fact we tend to incarcerate in ways that can and do lead to future victims (mostly other inmates and guards).
None the less, it is a universal norm that we punish people. Most parents involve punishment in their child rearing methods. A small few try to experiment with punishment free, but it is very difficult, in part because it is such an integral feature of society that many parents won't really understand that they are punishing their child, not just "disciplining". No one has really successfully created the "punishment free society". It is interesting to try to imagine one though.
= new reply since forum marked as read