The whole universe shrinkage thing as the OT progresses. It isn’t just the Luke/Leia/Vader family retcons, but that this paved the way for such a narrow focus in on-screen Star Wars material since.
I think the biggest example of this is that the Endor strike team is led by Han Solo, Princess Leia and Luke Skywalker just kinda because. There really should have been some more scenes (shots at least) of random rebel officers fighting the battle on Endor instead of just the main heroes and the Ewoks. (There is a grand total of ONE shot of just soldiers during the battle in Jedi; as opposed to the many in the battle of Hoth, a scene which actually plays out almost like a gritty war movie, at least the closest it gets to serious ground assault in the trilogy)