I think I've put my finger on what's always bothered me about that argument:

If the number of people who still act that way/believe it's right were actually a vanishing minority ostracized to the edges of society [like, I don't know, slave owners today?], I'm wondering if there might be a realm where it was still relevant enough for humor [if not novel] without being dangerous.

I'm thinking on my feet here, though...it might still not be worth it.