I agree that it’s a pretty bad idea to bring back Palpatine, and that the execution of that idea was also really bad, but this idea has been in the Star Wars universe for a long time - in the early 90s the Dark Empire comics were all about a clone of the emperor secretly working to assemble a powerful industrial and military machine in the galactic core, before going on a crusade to restore the galactic empire, with Luke Skywalker as his new enforcer, to replace Dark Vader.
The comics were and are extremely popular and a lot of the sequel movies seem to pull some ideas from them, but never in a way that really makes sense. For example, in Dark Empire, the republic has to deal with a mysterious new military force conducting heavy strip mining of planets long before they know anything of the new imperial threat.
It’s well known (and good) trait of Star Wars movies that they jump straight into the action without too much context, but the writing on episode 9 was so sloppy it feels amateurish. I’m not exaggerating when I say that I believe they could have got a fanfic author to do a better job. Delivering exposition like “somehow, palpatine has returned” directly to the audience is a fucking joke.
To be fair, though, I think the scenes on Exegol pretty much confirm that it was cloning, or some kind of Sith alchemy, and subsequent works (the Mandalorian, for example) are definitely leading in that direction, but that’s a post-hoc explanation for something that already damaged our immersion, not foreshadowing or a further explanation of something that was already plausible but a mystery.
I do think it’s a really good thing to have mystery in Star Wars, not everything needs to be explained and every new story should add new mysteries. I think things being mentioned and not explained (the Clone Wars mentioned in ep 4 being the best example of that, imo) is part of what makes the universe feel vast and real, like it has a full history that you could study for years. So I don’t agree with that “an intriguing story hook is shown and never explored” is always fair criticism. Sometimes it is, but often it’s just a cool mystery that will inevitably be answered in some minor novel or comic a few years later.
Anyways, I’m not saying they should have copied Dark Empire, or demonstrate/explain exactly how Palpatine returned or how he built his fleet. They should have just hinted at it by having the resistance interact with a new military force with a different aesthetic than the New Order. Have Rey bothered by a growing darkness that she assumes is Kylo, but reveal that Kylo had felt it too and doesn’t know what it is. Show the cloning vats and Sith alchemy on Exegol before we know that Palpatine’s back.
Definitely, 100%, don’t announce the twist villain of your movie on Fortnite to generate buzz. Make less money, probably, but a much better movie. I’ve written way too much in this comment, sorry, I’m having an autism/adhd moment