I agree with everything here (but the bolded bits!
).
I don’t think Rian Johnson did a very good job of making the eighth installment of a nine installment story. He left few/no strands to build towards an interesting culmination in the climactic Episode because he resolved basically everything. He needed to propel the story into IX; instead, he just told a story that happened to be the eighth movement out of nine. The middle chapter should position the pieces for the climax, not swipe the pieces off the board (in a dramatic -- not literal -- sense).
Consider the drama and intrigue still left unresolved at the end of THE EMPIRE STRIKES BACK: Han is captured. Luke is emotionally, spiritually, and physically defeated. Both of those angles send you out of the movie eagerly wanting to see how they're going to play out.
Heck, even ATTACK OF THE CLONES (and no, I'm not saying THE LAST JEDI is worse than AOTC) ends with the Clone Wars kicking into high gear and Anakin and Padme having a forbidden marriage.