It happens. It's one of those things in history. Concentration camps, for example, have been around since the Boer War when the British thought them up. Doesn't change the fact that it was a bad thing, but there have been bad things like that throughout history. The Assyrians kept peace in their empire by a policy of terror: flaying and beheading those who resisted. The Democracy of Athens actually voted to have the city of Milos I think it was utterly destroyed, its men killed and women and children sold into slavery. Just like our generation age does not have a monopoly on what is good, neither does it have the monopoly on what is evil. When one looks enough at history, one begins to see that nothing ever really changes in human nature. That is what history teaches. The holocaust is one in a long line of atrocities. It happened before, it happened then, and unfortunately, something like it WILL happen again.
My grandmother was in a concentration camp shortly after WWII, and she always says there were good soldiers and bad soldiers, and that terrible things happened, but such is life. I'd think it would be similar for the Jews. So to respond to what you said... they're very little good in it at all, save for the wise who will take it as a lesson. But there are few of those.