Because culture changes and a lot of people mature as they grow older and realise that comedy that is basically just mocking minorities is not actually funny and instead just lazy form of racism and bigotry by people who have no understanding of what they’re “joking” about so it’s just “something looks/sound different, so silly!”

It’s the same reason nobody feels like championing old racist jokes about the Irish or Poles or Italians. It’s hacky and unfunny and only people stuck in their contrarian teen edgelord phase would insist they’re great because of the racism of the era they were made in.