Three words: Ming always escapes.
Sorry, but this ain’t a 30’s serial. It’s 2020, audiences expect more complicated storytelling than just “he escaped.”
Anakin’s sacrifice is also clarified - His intention becomes unequivocally one of saving his son rather than doing another murder.
But the whole Chosen One thingy is about him destroying the Sith and bringing balance to the force. If he didn’t actually kill the last Sith, that makes the whole thing seem really stupid. I know some people didn’t like the prophecy, but that doesn’t mean you can just ignore it and pretend it never happened.
At least with him being a clone, you can justify that he technically died, but just came back a shell of his former self. Palpatine surviving Anakin’s sacrifice pretty much renders the entire George Lucas saga pointless.