I know it's technically no longer canon, but the Plagueis novel is so good. In the final scene, when Palpatine finally kills him, he feels uneasy about it. He has an eerie feeling come over him. I always loved the ambiguity of that, because I always felt that the way the book ended it was highly suggestive that Plagueis may have indeed cheated death again, or may have even survived in Palpatine somehow. At least that's how I interpreted it. It was definitely not meant as "Palpatine killed his master, the end. Nothing to see here."
Well, from what we learn in TROS, it turns out to be kind of relevant. Palpatine essentially IS "Plagueis". IE "All the Sith". The Rule of Two is not what we thought. A Sith apprentice killing their master in anger is what allows for the master's essence to pass into them. And so it goes on for generations. What TROS did was the most straight forward way to tie that all together, IMO. It gives a throughline for what Palpatine has been up to all along. He's been in search of a new, stronger body. It was supposed to be Anakin. Obi-Wan messed that up and turned him more machine than man. Then in ROTJ, we have him trying to turn Luke. Urging Luke to strike him down. Ever wonder what would've happened if Luke had actually done it? Now we know. That's pretty darn cool.
I liked some ideas in the DotF script, but I really really dislike the Tor Vallum stuff. I cannot get on board with using a brief appearance from Palpatine to prop up some new supposed big bad at the final hour, and then having that pretty much go nowhere on top of it. If this were a standalone film or trilogy? Sure! For the ninth film in a 9 film saga...no bueno. That just doesn't ring true. Not to mention it still seems to offer 0 context as to how Snoke fit into all of that.
I think Trevorrow's film might've been a better/tighter standalone movie, but I prefer how TROS connects the bigger picture stuff.
