I think it's important to remember the context William Golding was writing in when he wrote Lord of the Flies. His motivation was twofold, as I understand it. First, he was reacting specifically to an earlier castaway book in which a bunch of British schoolboys are stranded on...

an island and basically turn it into Gilligan's Island, subtextually demonstrating that British upperclass children have an inherent superiority over the "savages" who live in the Pacific and elsewhere that have done less with more. Golding was like, "that's BS."

He was also reacting to the collective trauma of the Holocaust, where people very similar to the ones who ran the British Empire committed the most "savage" acts imaginable. His premise was, being white and upper class doesn't make you superior to someone who would murder...

for a dead pig god. So yes, his view of humanity is bleak, and in comparison to a group of ACTUAL castaway school children from the same time period (even if at least some of them weren't white and none QUITE as privileged as his characters) quite wrong.

We are better than William Golding told us we would be in a crisis. But he still had a point. Our worst traits come from somewhere. He was right that our best traits don't come from being in a privileged race and class. Maybe he was wrong about where our worst ones come from.

Maybe our worst traits come from the very thing his fictional school children only had a little of, that the Nazis and colonizers had much more of. Maybe we can only really kill for the dead pig god when we have "civilization," by which I mean...

when we have a system we can export our culpability to, a structure we can blame and say, "it's not me, I never killed for the pig god, those deaths were an unfortunate systemic necessity. I was merely doing my job."

What I'm saying is, the plot of Lord of the Flies does actually make sense. But maybe it only makes sense when those kids are at boarding school. As soon as they're stuck on that island, the chances of it happening should go way down.

TL, DR; William Golding's point was that Lord of the Flies doesn't happen based on race. It could happen to anyone. I think Lord of the Flies happens not due to an excess of passion and lack of structure, but from a lack of passion (read: empathy) and an excess of structure.