Because when the original films were made the back story hadn't been fleshed out yet.
Darth Vader wasn't originally supposed to be Luke's father, for one thing. That's why Obi-Wan tells Luke that Vader killed his father. In Jedi they play that off as Obi-Wan being figurative, that the Darth Vader persona "killed" the good man who was Anakin Skywalker. But originally, Luke's father was another Jedi who had been murdered by Vader. But when Lucas was writing the script for Empire he wanted to include a twist and he came up with the idea of Vader as Luke's father.
Similarly, R2 and threepio were just supposed to be some random droids who became involved in this great adventure basically through happenstance. That's why Obi-Wan claims to have never owned a droid like that before, because he hadn't. R2 was just some random droid that Leia grabbed and put her message into. But after three movies, R2 and threepio were seen as integral parts of the Star Wars universe. When they made the prequels the human characters couldn't appear, obviously, because it was too long ago. But the droids could appear. So Lucas included them. This set up continuity problems because Obi-Wan didn't remember the droids at all, despite having lived with them for several years during the prequels. And the droids, at least Threepio, didn't seem to remember anything from before. While R2 is pretty inscrutable and unflappable it defies belief that Threepio wouldn't mention that he and Obi-Wan knew each other. And Threepio's nervousness in the original trilogy seems harder to buy once he;s been through all the adventures in the prequels.
The prequels also set up other continuity problems. At the end of Revenge of the Sith, Obi-Wan and Yoda go into hiding specifically to await Luke and Leia becoming adults who can then be used to take down the Emperor. But when Luke shows up they don't seem to show any interest. Obi-Wan agrees to train Luke and take him adventuring but there seems to be no interest beyond him being a force sensitive boy. Yoda is even worse since he seems to actively reject Luke's interests in training with him.
· 4 weeks ago