I listened to Critical Drinker's review of Star Wars Rise of Skywalker. I conclude that since the conflict was repetitive & unimaginative, the whole action plot followed suit. The Rogue One prequel had the Death Star and Darth Vader as the ultimate villains, so that conflict was acceptable. Episodes 1-3 had Palpatine as the villain & the rise of the empire. 4-6 featured the Rebel Alliance against the full powered Empire. In 7-9, it sounded like the Empire was resurgent.
Timothy Zahn's Star Wars novels, which were sequels to 4-6, featured an Alliance that strained at the seams to hold together, while pushing back a reeling Empire. In the novels, the Empire never threatened, leaving the story rather unsatisfying.
With the MC Rey, the remnants of the Empire never threatened either. Without good antagonists, the action movie does not hang together. To have a disillusioned Luke, it would have made more sense to have the Alliance fall apart from the inside with old divisions & wars that were suppressed by the Empire flare back up. It is easy to imagine in the light of the post-Cold War flare ups.
That way, there would be moral ambiguity. Was there even a temptation of the Dark Side for Rey's soul? Or was she too pure for that?
A real play for her soul would have been the offer of power to stop all of the conflicts around the galaxy.
Another complaint from Critical Drink was the reprisal of the "Luke, I am your Father," scene was not so much as a reveal, but a jack in a box that is sprung on the audience. Instead of a direct lineage, the Emperor could have had his DNA spread throughout the galaxy. They would have been spread secretly high and low to see what would survive in a Darwinian winnowing of those who would succeed in surviving and see reality stripped of the niceties. Instead, there would be the survival of the strong to meet the greatest threats.
Surviving a lifetime of poverty, Rey could have relied on the Dark Side to make her way. After Luke left the Alliance to find a new way without direct force, the remaining members would look for a new leader/figurehead/force user. They would find a smart & plucky Rey.
It would make sense that the Emperor would not put all of his eggs in one basket. One of the seeds would have been Rey. The Emporer could have also left a legacy for the future Sith that reached the top. Rey could reject that legacy as well. Hell, I would settle for the gurl power message that she really is independent & don't need no man, Empreor, bicycle. This possible temptation could be mutually exclusive of the power to enforce order in the Universe.