a slap in the face to justice and to civilized society.
not nearly as big a slap as when we kill the wrong guy and then cover it up
One of the (perhaps the greatest) signs about what we as a society value is by the severity of punishment doled out to those who violate those values.
No punishment for abortion indicates we value unborn human life at the level of chum. Perhaps less, since there are, no doubt, regulations in certain localities about what one can dump in the ocean or how critters are treated in captivity.
The death penalty for murder indicates we value innocent human life more than if we had no penalty whatsoever. Any lesser punishment is just quibbling.
From a practical perspective, the death penalty is society engaging in self-defense. Most murderers who get the DP are not retards who got tripped up by clever interrogators or regular folk who just snapped. They have a long & sordid record that pointed toward bigger & badder crimes.
Execution being final is used as an argument against the DP. Personally, I find finality its greatest argument in favor. Never in recorded history has a man been successfully executed and gone on to commit more crimes, as many who have had life sentences have done. To include murder.
Also, do we not care about those convicted of lesser crimes? Aside from not affording them the panoply of legal resources DP convicts get, locking them up with folks with nothing to lose (life sentence w/o parole and no DP) is a good way to ensure folks who don't deserve the DP get it on the sly via outright murder or by contracting AIDS/hepatitis/etc. Or, even if they don't die from it, tossing on multiple anal rapes on top of a few years in prison seems a heck of a lot more unjust than sending a convicted murderer to Hell (or the underworld of their choice).
WRT prosecutorial misconduct, I think that prosecutors need an IA division as much as police do. Placing them in jeopardy of receiving the same penalty if they hide exculpatory evidence or otherwise knowingly send an innocent man to prison is fair.
I would second the notion of alternative punitive measures rather than time behind bars. Corporal punishment, such as "X lashes for Y crime" would be much preferable.