I've commented before about my love of Utopian scifi and the way in which it can inspire and motivate us. Star Trek, is, of course, my main reference there - it had a huge impact on popular culture, and, in my mind, one of the major elements that makes it Utopian is the nonlethal uses of force. Phasers set to stun, Vulcan neck pinches... in the absence of entirely nonviolent conflict resolution, they're the next best thing.
(It's worth noting that Lily's Florenovia stories featured no violence at all, and when she shoehorned it into the tabletop game, it was Ellen who figured out how to subdue the Right to Motherhood without hurting them. Star Trek would have been a very different show if Kirk took out Romulans and Klingons by making them all insatiably horny and/or itchy.)
Sadly, in the real world, our stun-phasers are still a ways off. Tools such as tasers, pepper spray, fire hoses... it goes without saying, they're all more than capable of causing lasting harm, and are prone to misuse and abuse. As long as guns exist and are available to criminals, police officers will also have to carry them and be trained in their use.
And, as Cheryl herself has said, while a handgun may theoretically be used for other purposes, its primary intended function is the ending of human life. You don't fire on someone with the intent of blowing out their kneecaps or knocking a weapon out of their hand or disabling their vehicle. Unless you're Vash the Stampede, if you fire on someone, it's because you're trying to kill them.
I do think it's a valid concern, the idea that if you train to be proficient in firearm use (as you should, if you're planning on carrying a firearm), that you're necessarily training to kill human beings. Whether this makes you more inclined to take life or to think of homicide as a viable protoplan is a matter for psychologists. Certainly, there's plenty of news out of the States right now that would seem to point in that direction.
When the primary tool in your toolbox is a hammer, a lot of your problems look like nails. And, when you feel like a nail, a lot of people coming towards you look like they're carrying hammers.
You know who I blame? Richard Nixon.
It's the whole "War on Drugs" and "War on Crime" mindset. Wars are great for motivating people, but they also turn any conflict into a conflict between two sides. In theory, police work is a single body healing itself. We are helping to fix Us. Once we reframe it as a "war", though, it becomes Us versus Them... and has the unintended side effect of legitimizing their counterattack. If two armies are fighting each other in a war, then neither sides' actions are murder - if police are really in a war against crime, then neither police killing criminals nor criminals killing police are really wrong. That's just how war is supposed to go.
Anyway, this is all just to say that the invention of the stun-phaser would be really nice. Any day now.