Star Wars: A question of scope.

[DWF]

Just the fact Luke and Leia became intricately tied to the main villain made them more important than they were before. Instead of just a random princess and a random farm boy, they were now part of a hugely important "Skywalker family" upon which the fate of the entire galaxy hinged.

Exactly. It wasn't until later drafts of Empire that Vader became Luke's father, and it wasn't until the Sequel Trilogy was compressed into Return of the Jedi that Leia became Luke's sister. (The clearest indication that Leia and Luke weren't related is Alan Dean Foster's Splinter of the Mind's Eye.)

I think that the changes were brought about by Lucas believing he was writing something important -- and something mythical in a way that Joseph Campbell would recognize.

I think the Joseph Campbell reference came as an afterthought, I think Lucas understood the history of storytelling and movie making and just put the two together, quite without realizing that it fit into Campbell's Hero's Journey.

 

[Flying Spaghetti Monster]

Scope has been a a problem in this saga, however, FWIW, I think that ESB actually expanded the scope of the story from ANH. Sure, the characters might have become more important than normal, but there were certain small things that ESB did to expand the size of the SW universe.

- Cloud City.. here is an awesome city in the clouds, like nothing ever scene in film before, with expansive sets to match. Yet, the operation is small enough not be noticed under most circumstances, be it by the Empire or the mining guild. If Solo hadn't gone there, the facility might not have ever been noticed by the Empire

- The carbon freezing room. Also a wonderful, expansive set, unlike anyhting the audience has ever scene, but tossed aside by Vader as "crude"

There are other references as well. I believe that the reduction in scope started with ROTJ and in the prequels, more planets wre seen but every planet was so much more important and there were many plot contrivances (engine leaking, land on Tatooine) that make it all seem very small