Context is everything. For example, this scene uses blackface, but is a scathingly hilarious satire of media hysteria, and the absurdity of demonising entire people groups en masse.

https://www.youtube.com/watch?v=stMdInZdxlM

And yes - a lot of Americans don't get the nuances of British satire, or our long tradition of mocking our leaders in cartoons, caricatures, etc. Though not all Americans, to be clear. :)