As a youthful GM back in the 80s I ran Keep on the Borderlands. And in this adventure (and others I'm sure but names are escaping me) the writing specifically said there were children in the caves. So, naïve little fella I was, I just ran it as written. I mean, it made sense to me that there were children.
No-one liked that there were children. They were like "Dude, we don't want to kill children but we don't want the hassle of running an orphanage either. Can we just say there's no kids?" I'll be honest, I was a bit "but, it's village of people, of course there's kids." The players said "We don't care about the realism." I didn't want any child murder either, so no kids it was.
The downside of that was that we could continue playing the simplistic "they're bad guys, kill 'em all" style of game.
It was only once we started playing games other than DnD that we moved away from that. Palladium had orcs (goblins, ogres, trolls) playable as PCs. Shadowrun/Cyberpunk was a real change-up as we could see that the NPCs (e.g. the security guards) were just people with jobs, they were specifically presented as such in the rule books and adventures. Marvel FASERIP made killing anyone, even Red Skull, a bad thing. (Murder's a bad thing? Who knew?) Being a murder hobo was suddenly a lot harder.
I guess what I'm slowly waffling toward is that the way a game presents in-game situations has a big influence on how it's played. DnD has only moved away from murder hoboing in recent years. But did anyone playing Shadowrun, even in the 80s/90s, ever think it would be okay to walk into a big squat in the Barrens and start murdering all the people, be they orcs, dwarfs, humans, who lived there? I'm gonna guess no-one did that. I know in my Shadowrun game we very rapidly moved to gel rounds and narcojets for all but the most dire situations.
