I'm not saying I think kids have to have their faces shoved into the ugly side of things, but I think kids ARE more knowledgeable these days and have greater access to the horrible truths about human slavery and such. And I think they should know about it - because being aware is how you stop from repeating the mistakes of history.
I also agree about kids being extremely resilient. They can take a LOT of facts into their heads, like sponges, and not be destroyed by such knowledge. Of course parents don't want to imagine their kids having to see or know about unpleasant stuff - but sometimes that's the way to teach examples of how we, as humans, have failed each other.
For example (as a Boomer myself), in driver's ed we had to watch gory accident movies filmed by the police, including things that would turn a hardcore horror fan's stomach. Nobody enjoyed (I HOPE) watching those things, but you can bet they scared some of us silly enough to be cautionary drivers and be more careful behind the wheel.
No, the truth isn't always beautiful, it can be harsh and disturbing. Yet not facing it always results in more bad outcomes.