Please explain how using a mouse and keyboard or a controller translates to being able to better use a gun. I suppose these kids all know how to use swords like Samurai as well now.
There is absolutely no similarity between sitting on your ass staring at a screen and running around with a gun killing people.
Maybe you should run the google search 'attacks with samurai sword' before you display such certainty that gameworld will not overflow into realworld. If random murder is just 'good clean fun' fit for entertainment, what will you do when 'Grand Theft Pedophile' or 'The Grooming Game' comes out. Please feel free to not answer the question with some kind of ridicule about future crime, but at heart the question is where do we draw the line on perversity as entertainment
It's not whether games make you a better swordsman, it's whether they abrade the layers of civilization meant to keep you from solving your problems with a weapon. Why do we teach rigorous safe gun handling and respect for the capabilities of the weapons? Why is personal honor and restraint such a large part of most (worthwhile) teaching of martial arts? Is it because we want to strangle any idea that a weapon be used for any other purpose than defense of oneself and innocent others and even then as a last resort? And is it possible wholesale killing positioned as revenge or entertainment weakens those lessons?