I guess the nature of Star Wars always being presented as not the first chronological instalment, and being rebranded as “Episode Four” as early as the following instalment, is why I don’t feel it’s different.

We still don’t need to know more about him, because he’s by his very nature a force to push Kylo Ren in his development. It doesn’t matter how Snoke came to power, what matters is he is in power, and how he’s using that power. Again, looking at Johnson’s intention (Abrams didn’t really have any coherent vision or plan, so he’s not worth looking at in this capacity), the plan was to have Snoke killed by Kylo and set up Kylo as the big bad. This shifts importance onto Kylo’s backstory, which was developed quite well across the films.

Rian even talked about this, saying that a reveal of who Snoke was or how he came to be wouldn’t really change anything for the characters in the story. He’s right. None of our characters care about the how, they want to combat him.

What you’re talking about is an audience desire, not something that would actually serve the story. Contrast this with Palpatine’s return. With Palpatine, we need more information because his reappearance contradicts his death that we’d already seen. Snoke arrives from a previously unexplored place, literally called the Unknown Regions, so his arrival and rise to power does not contradict any prior story. Information about him doesn’t impact anything about the story, partially because he wasn’t in those prior instalments. Even if he had been a crime lord, or Darth Plagueis and Palpatine’s teacher… it wouldn’t matter. His backstory only matters if he comes into contact with someone he had a shared past with.