A puppet being operated by the real villain?
But why have a dime store Palpatine if the plan all along was to use the real thing?
Because that’s how Palpatine operates. Masks, deceptions and lies. Snoke was just a more sophisticated version of wearing a hood and keeping his face in a strategically placed shadow.
That’s a nice in-universe explanation, but in reality it’s almost certain, that JJ intended for Snoke to be the big bad, and when RJ dispatched him, they had to bring back Palpatine in some form to up the ante. Had it been their intention to bring back Palpatine, they would logically have introduced him as the puppet master in a cameo at the end of TLJ. Additionally RJ clearly made TLJ with the intention to break free from what came before, whilst TROS seems to do the opposite promising a whole host of connections to the past.
I have to disagree with your interpretation of TLJ. That is the message that hermit Luke and Kylo Ren share. Both are proved wrong by the rest of the movie’s plot. The end of the movie is about embracing exactly what Luke said they didn’t need before Rey and Yoda brought him back to himself. And Kylo is trying desperately to be bad and be consumed by the dark side and yet he can’t seem to manage it. He’s trying to convince himself that he needs to destroy the past so he can be bad enough. But that is not RJ’s message in TLJ. Luke executes the very single handed battle with his lasersword against incredible odds and creates a legend, reminding Kylo and us that he will not be the last Jedi - meaning he is embracing the past and letting it carry forward. Quite the opposite of breaking free from what came before. And there is no hint that JJ is going to undo anything.
Snoke was the bad guy, but when you think about it, we know as little about him as we knew about the Emperor in the OT. He was just a figure mentioned in conversation in ANH. He appeared briefly in a hologram in TESB, and only with his arrival on the Death Star in ROTJ do we really get a feeling of his personality. But we had no back story until the PT. Abrams has been going for that feeling with Snoke - the unfleshed out bad guy at the top. What we get in TROS is going to be something to end the saga (which they have been saying all along that IX was going to do) so who knows what secrets it might reveal. The spoilers have a lot of guesses on Palpatine’s role and there are ways to tie it all in AND tell us more about Snoke if there is a reason to. But he died as backstoryless as Palpatine did back in 1983 (when we had no idea how he came to power or any of his history).
The difference being that the OT were the only movies at that time. Snoke on the other hand is a character that is coming in with six movies behind him. That begs for context in a way that The Emperor did not.
JJ was trying to recreate the OT’s approach, yes, but that’s a farcical idea when the backstory actually exists now.