I first wrote about the desensitization to killing back in the 70s. We watched Movies and TV where the good guy killed bad guys and the bad guys had the good graces to just fall down and be dead. Now a days in video games they don't even leave a carcass behind, just poof away.
I imagine the first time somebody would plunge a knife or sword into a person that needed it that they would be mighty surprised at the amount of blood that can gush from a human. Lots of shooters are really surprised at the violence and just how hard people can fight back when their lives are at stake.
You know what? This is getting completely out of control and I will come back later to actually answer your most excellent post. I'll have my soap box completely put away by then.
Sun Tzu wrote something like. always give your enemies an exit, no one fights harder than with their back against the wall.
I think it is not just desensitization, it is also productization. We have made ourselves products and therefore, we are disposable and without feeling, thought or life of value. We have created a society of strangers, while we discount and treat badly the people who actually care about us.
Nothing wrong with soap boxes, it is good to air thoughts :)