Death penalty is immoral in all cases. The discussion ends right there.
Now, that said, I also think keeping criminals housed and fed for free on the backs of tax payers is immoral. Furthermore, if the goal of criminal justice is restitution, simply jailing criminals does little for the victims.
Forced labor for a salary, and sending that salary or most of it after living expenses (in jail) to the victim as restitution sounds like a better option overall.
I think, victims feel better with their perpetrators in jail, so it does something for them.
With the expensive US jails, there is no way the average criminal could pay for their own "expenses" and much less for payments to their victims. Bringing down these costs could do more for the tax payer than to make them work.
I agree that it may be partial comfort. I think the victim of a crime should have a say in what sort of compensation they can demand, within an arbitrary range of options set by social custom and morality, which includes things like proportionality and no death penalty.
US jails are expensive only because the current system of jail contracts paid for with the taxpayer's money is a source of massive corruption.
