Not gratuitous sadism. Merely a necessary warning to show these killers what will happen. Going to sleep is not a deterrent for many of them.
Just like they used to put Muslim heads on pikes to make sure the bastards know what lies ahead.
Nobody wants to do it. But it sure beats having your daughter taken by the hordes
It will destroy the would if those who carry out the sadistic punishment, those witness it, those who approve it, and the nation that imposes it.
Those who are deeply psychically attracted to cruelty will derive gratification from it, and you may even get copycat crimes. Don’t think hell-bent personalities are deterred by degradation and pain, not even their own.
Nietzsche spoke the truth when he said you must beware when fighting dragons, that you do not become one.