A few of us are in support of public hangings for the worst of the criminals - those who have absolutely no regard for life, and take pleasure in the suffering of others (and many traitors fit into that category).
So why? Is it some twisted thing? Do we like seeing people die? I can assure you, I don't like seeing people die - I know what it looks like.
First off, there are some people that need to be punished to the full extent of the law. No ifs, ands, or buts. They did what they did, knowingly, and without excuse (wealth and power removes a lot of excuses).
Second, these same people have the connections and resources to escape justice, and to have other people die in their place if necessary, to save their own skin, even if it's only for the short time they have left on this planet.
Third, a death sentence is the only hope to save some of their souls. It's a funny thing to think that is even possible, but God values souls differently than we do.
Fourth, we need to know they are being punished for their crimes. Otherwise, where is the rule of law?
Fifth, evil doers need to know they are going to be punished. Evil is encouraged when they think they are going to get away with.
Sixth, to protect the children. Evil most often targets the weak and the helpless.
And whereas the reformation of offenders, tho' an object worthy the attention of the laws, is not effected at all by capital punishments, which exterminate instead of reforming, and should be the last melancholy resource against those whose existence is become inconsistent with the safety of their fellow citizens, which also weaken the state by cutting off so many who, if reformed, might be restored sound members to society, who, even under a course of correction, might be rendered useful in various labors for the public, and would be living and long continued spectacles to deter others from committing the like offences.
Thomas Jefferson Bill for Apportioning Crimes and Punishments, 1778
Thomas Jefferson was not opposed to the death penalty. He believed that a citizen used up his "social contract" rights to life under two conditions: heinous, aggravated murder, and treason against one's country.
"Human" monsters exist.
If normal people see that monsters can continue being monsters with no punishment, there's no point in having a society anymore.