Metaphysicist
Not Actually Brian Hunter
But why though? why does there need to be more? Again what info is there in any other trilogy? How did the republic come into existence? How did the Jedi Order build a grand temple on the capital world of Coruscant? How did the rebel alliance get any of it's funding? How did the Empire rule the Galaxy? Why aren't everyone rebelling against the Empire? I could go on, there's tons of things that weren't explained in the films. They were expanded on in other mediums like film, books, comics, etc. Snoke could easily be a very wealthy and powerful dark side user who existed in the Unknown Regions who took over the remnants of the Empire. There's a number of things it coudl have been. It doens't really matter. Snoke isn't a star of the film, he's there to be the trainer of Kylo Ren. He's there to be the Emperor to Vader in the OT.
I do mostly agree that the writing of 7 is kind of all over the place. The whole Luke MacGuffin was abit of a drag all information considered.
Why do I want movies to make sense based on the preexisting universe? I dunno, that just seems better to me. Call me crazy.
Your examples are all world-building in a new space (or boring). That is fundamentally different.