I would argue Lucas committed an “original sin” when writing Star Wars in 1975.
He’d wanted to demonstrate the Empire’s cruelty by showing the graphic aftermath of Leia’s torture in Vader’s prison. But by the end of 1975, with budget cuts pressing on him and the management at Fox doubtful about the prospects of his little space-opera film, Lucas began to panic: he’d already started thinking of SW as a story spread over multiple films, and he didn’t want it derailed at the very first outing. The failure of THX 1138_ in the movie theaters still haunted his mind.
So he decided he needed to maximize the revenue from SW to improve the prospects of a sequel. The best way to do this was by avoiding an R rating, keeping Star Wars open to all ages. The stark realities of Imperial torture, meant as a commentary on Vietnam and the US military-industrial complex, were tidied off-screen in the name of family-friendly moviegoing. It paid off: Star Wars was a massive hit at the box office.
But there were consequences. In-universe, Lucas struggled to come up with alternative ways to depict the Empire as a credible threat to the heroes. His solution, worked out during filming, was to kill off Obi-Wan on the Death Star. This in turn led to the problem of who Luke’s Jedi mentor would be in future films. And if Obi-Wan could show up as a ghost, why couldn’t Luke’s father do the same? Wouldn’t having two ghost mentors be a little crowded? This problem of story-crafting, the result of hasty alterations to the first film, ultimately led to the merging of Darth Vader and Luke’s father, who had previously been two separate characters.
And in the real world, the politics of Star Wars became so anodyne, so essentially unthreatening, that anyone could identify with the Rebels fightin against the evil Empire. Most famously, Ronald Reagan adopted this rhetoric in spades, so much so that his SDI missile defense system quickly was dubbed “Star Wars” by the press. The sort of Goldwaterite conservatism that Lucas had railed against in the early 1970s had now co-opted his film franchise in the public mind.
And no one, outside of a very small coterie, ever expected that George Lucas would make another R-rated film.