I grew up on post-WWII America in NYC. I went to Catholic schools in an era when that Church was searching its soul (remember Pope John XXIII?) as it contemplated how The Holocaust could have occurred. How could such a civilized people as the Germans have descended into such barbarism? How complicit had been the Church and how should it deal with its consequent responsibility?
That period of reflection so informed my education that I can never "divorce" an artist like Leni R. from how she used her talent.
Subsequent genocidal atrocities like Cambodia in the 1970's, Rwanda in the 1990's or Darfur today are irrelevant to me in creating some sort of moral relativism about what occurred in The Holocaust. Later evil does not excuse, nor explain away, what occurred in Germany in that period if only because, in my admittedly Western conceit, I would have expected much better from the Germans than any of those others!
That the people of Goethe, Beethoven and Kant (for example) could have descended into such barbarism is - on reflection - a frightening indictment of humanity.
In conclusion to my input to this thread, that some talented Germans such as Leni R. were willing to allow their gifts to be used to glorify a descent into such barbarism is, to me, totally inexcusable. Many talented Germans left that country in the 1930's rather than submit their gifts to advance the evil cause of Hitler and the Nazis. Leni R. chose to stay and benefit from doing so.
I have no respect for her and no reason to regard her work in any kind of positive light. There are limits - she crossed them.