How do you define exclusion as justice? What if hypothetically 100 years from now we create a system/program that "rehabilitates" a convict within 10 minutes? Will you be ok if that person is let out after 10 minutes? I think we need to obtain a balance between the wronged individual's grievances and the order of a society. I'm not saying make the family judge, jury and executioner or bring back public executions. But they should have a closure to their loss. I'm saying we need not go overboard by having the convict continue to enjoy the life's comforts like playing PS3 inside their jails.
Even if I totally agreed with you, there aren't only murders in prisons, they make up an incredibly small part of the population. A person who robs a bank and is arrested and all the money recovered. What does the bank get out of this person being miserable for 20 years? How is that beneficial? They got the money back and the guy is put away so he can't rob other banks. Taking efforts to rehabilitate him is absolutely the correct way to go.