Let’s say you hypothetically agree that the state should reserve the power to execute some people, in very very rare cases. Well cruel and unusual punishment is supposed to be unconstitutional. And all the chemical companies refuse to sell the injection chemical. And testing out new methods is obviously pretty cruel…
Focusing on the unpleasantness could actually get us closer to a place where effectively no capital punishment occurs due to these limiting factors. Without even getting the average American on board with the idea that executions should be banned entirely.