There's a fine line between fun happy combat and ... um ... uncomfortable colonialist massacre of women and children, if you catch my drift
IMO there are fine lines on some axes, and wide gaps on other axes.
I've enjoyed sparring, which is a form of violence, though intentionally and drastically limited violence; we were trying to *hit* each other, just not for significant damage. It was fun happy combat. It was different from colonialist massacre of women and children.
I've used physical violence once in my adult life, to stop a man who was holding a woman down on the sidewalk, and repeatedly punching her. That was not sparring; it was the real thing. I used minimal force, enough that she could get away, without doing him any permanent harm - but I had accepted non-zero risk of permanent harm to myself, had certain factors turned out differently, and if I'd been unable to limit how far the situation escalated. (Fortunately for me, he turned out to be unarmed, mentally disorganized, and smaller than me in both reach and mass.)
Again, that was real violence, and it was NOT "colonialist massacre of women and children". He and I were both white men; no one died; I did not subsequently take his hunting grounds and turn them into a plantation.
During the Third Reich occupation of the Warsaw ghetto, there was mutual violence between Jewish civilians and German soldiers. There is a TRPG, in which the PCs are members of the Resistance. It has a grim tone, but the players may reasonably consider (some of) their PCs to be heroes (of a sort). I am not aware of a published TRPG in which the PCs are soldiers in the German army, assigned to crushing resistance in Warsaw. (Though I am aware of white supremacist TRPGs.) It's as if though both Jewish snipers firing at German soldiers, and German soldiers firing at Jewish volunteers, are both practicing violence, many players see a *moral* difference between one side's use of violence and the other side's use of violence. More or less the same applies to "Golden Age Champions"; the setting book assumes that the PCs are on the side of the Allies.
So there's a valid general question about why so many of us, play so many games with *any kind of violence*.
There is also a MUCH more specific question about why so many of us play - or have played - games which specifically include colonialist massacre of women and children (whether human or humanoid). In AD&D, high level PCs don't just slaughter orcs without second thoughts; PCs even exterminate "monsters" in a designated territory, so that human or demi-human farmers will arrive, build farms on the land, and then pay taxes to the PC, so long as the PC builds and maintains a keep. Yup, there's specific rules for that process.
When did non-colonialist games emerge (that is, games *without* built-in rules for the endgame of becoming a tax-collecting, monster-eradicating plantation overlord), and to what extent have some players preferred those games, specifically on that basis?