I’ve come up with a great analogy for why Anakin’s turn doesn’t work.
Imagine you have a romantic partner and they get into a terrible car accident. You’ve been in the hospital for 3 days and there’s a possibility she may die. You’re worried sick and have barely slept. Satan himself (for the record, I’m an atheist, but this is hypothetical) appears to you and says, “I’ll save her if you kill all of your neighbors, coworkers and their families, every friend you’ve ever had and their families, your entire extended family, and your partner’s entire extended family. This includes any of the children or babies.”
Who would do that?
There has to be some parallel between Anakin being tricked into becoming Space Hitler and the Senate being tricked into becoming Space Nazi Germany, though. I don’t think this is a mistake or a failure of the prequels, but genuinely how George Lucas views the world, or at least the message he was trying to convey.