People are legit hung up on the Emperor having a kid? And a kid that decided having space Hitler as his dad isn't a good look so disowned his Hitler dad a bad thing why? And people are also arguing that he doesn't look older than 30 when in the same film series we have Ewan MacGregor turning into Alec Guinness in the span of 19 years?
Come on, guys. There's being pedantic, and there's being PEDANTIC. Jesus Christ.
At the end of the day, these are still movies aimed at a younger audience, and the focus is going to always be on the protagonists, so going into excruciating detail about the antagonists and their history isn't going to happen. We get just enough meat on the villain bone to establish that they are the villains. It's what made Kylo Ren so interesting of an antagonist, because he was the first Star Wars antagonist in the films to be more than 2 dimensional, black and white evil. Before the prequels, all we knew of Vader is that he was:
ANH: A former Jedi pupil of Obi-Wans who went to the dark side.
ESB: The right hand man of the Emperor (who we also see for the first time in this movie), and Luke Skywalker's father.
ROTJ: Conflicted between his loyalty to the Emperor, and his familial connection with his son. He had given up hope of redemption until Luke's unwavering faith that there was still good in him was the spark that was needed to turn him back to the light, and at the least, reconnect him with the light side of the Force and his son before he died, even if most of the Galaxy will still forever see him as Darth Vader, sociopathic child murderer.
As far as Palpatine goes, I don't find it hard to believe that the Emperor of the Galaxy has groupies. Power is attractive to many people, man or woman. I guarantee there was no shortage of sycophants that would cozy up to Palpatine.
So let's go down that rabbit hole. Emperor Palpatine meets a woman attracted to his power. They hook up (it's not like people don't fuck in the Star Wars universe, we just don't see it on screen). It's also possible that in a universe with hyperdrive travel, he may have gone the IVF route to ensure that his line would continue in some capacity. No actual sex involved.
Anyway, his devotee gets pregnant. And maybe she has a crisis of conscious during or before RoTJ happens, and she takes her child (does TRoS say Rey's father or mother is Palpatine's kid? I can't remember), and she flees Palpatine before he can reclaim his kid. She goes into hiding (not a foreign concept in Star Wars). She raises the kid into adulthood, they meet their spouse, have Rey, raise her on Jakku (maybe her parents were also raised on Jakku, which is why they were junk traders in the same way Luke worked on a moisture farm), then when she's 5 or 6, Palpatine's specter or cultist followers discover that Palpatine's offspring lives, track them to Jakku, and we're off.
Maybe Ochi has no idea they had a kid. Film storytelling and editing, Rey was shouting at a ship that was really, really far away. And since when have Star Wars ships had rearview mirrors? That complaint is so stupid to me. If Ochi was unaware that they had a daughter, he wouldn't be looking for one, let alone a little girl yelling in her little girl voice at a ship that was already in the atmosphere, blasting into space with its engines firing.
There's a lot to criticize about the movie, but the sheer lengths people are going to keep their nerd rage going is a little weird. You don't have to nitpick the movie to death to justify why you dislike it.