The focus on method, in other words, is an effort to take something awful and brutal and dress it up real pretty until it is acceptable fodder for dinner table conversations. Capital punishment suffers as a political issue for our tendency to argue about tangents. Is the death penalty “right”? Well who gives a shit about whether it is morally right or wrong when it and the entire justice system are demonstrably flawed in practice. Which method is the most humane? That’s a red herring intended to condition people to accept the death penalty as inevitable by pushing the conversation forward to arguing style.
Is lethal injection cruel? Sure. So is the firing squad and the electric chair and every other method devised and put to use throughout our history. It is cruel inasmuch as capital punishment is cruel; our methods are barbaric inasmuch as the concept itself is barbaric. No amount of window dressing can make the act of killing the people least able to leverage social power and privilege over the justice system seem dignified. If all of our methods seem ugly it is because what we are doing is ugly.