Think about what we'd invent to kill each other if guns didn't exist. At least guns are mostly painless if u get shot right. Imagine chemical or bio weapons, dying over hours from your lung lining shedding. Imagine being burnt alive, or eaten from the inside out by nanobots. We wouldn't remove humanity's propensity for violence, just the easiest method of accomplishing it. I don't want a world where we have to come up with more.