Hmm, I guess I can see that Snoke has no arc at all, but I don’t think he was ever supposed to be more than just a prop for Kylo Ren, an actual main character. He has no more or less of an arc than Yoda or Obi-Wan in the OT, who exist to serve Luke’s character, or Dooku and Grievous in the PT, who similarly are static character who serve plot purposes and at best foreshadow elements of Anakin’s future. There’s only so much you can do in seven or so hours. Luke on the other hand has a pretty major arc, all about forgiving himself and re-embracing the Jedi - if he was already that way at the start of TLJ, I don’t think it’d be so divisive. I certainly agree there’s a perceptible change in direction between movies, but I feel like that’s a different complaint to static characters.