Having prisons teeming with prisoners is not best for society because it is incredibly expensive. More expensive than getting them therapy that is for certain. No I do not believe in the death penalty.
The justice system is not there to get retribution for victims, that is misconstruing its purpose. That is, by defnition, a private matter and to be settled in a civil suit. The criminal justice system is there to punish or rehabilitate offenders as it is appropriate.
I would argue that the question of rehabilitation or incarceration should be answered based upon what will benefit society most.
I doubt I would be happy at any sentence for a murderer because it would never replace a loved one. However, I feel like people keep forgetting that this is a 16 year-old we are talking about here. I would like to think I have enough compassion to see that a long period of time in jail will not be as good for a teenager as counselling would be. If it was my loved one, maybe I wouldn't, but as I mentioned above, the criminal justice system is not there to get retribution for the victims.