I think Rian Johnson was given an incredibly difficult task after Force Awakens. That movie left the Star Wars galaxy in a relatively boring place by resetting everything. The sequel trilogy should have been set in a still young and burgeoning Republic with the potential for all kinds of new storylines; a rehash of the Rebellion vs. the Empire was a bad idea. It set up the following movies to be completely stagnant from a plot standpoint.
I would disagree.
Rian is the one that reset the trilogy completely. As that's what he needed for his deconstructed take on Star Wars. JJ rehashed large plot elements but it was still a new story, new characters and roles which could unfold in many different ways. The First Order was not the Empire in JJ's film.
"The First Order reigns."
These words reset it.
There could have been countless power dynamics in the galaxy if anything this is the least expected.
Rian abandoned the new story, deconstructed Star Wars to the basic premise of the Original trilogy. It's the middle film, there for the main plot is that of The Empire Strikes Back. Escape hidden base, but didn't really escape. Star Wars is about young hero who discovers they have a power, they seek guidance from wise old mentors and are connected to the bad guy. They resist the dark side, team up with the bad guy to defeat the really bad guy.
Rian laid this simple plot across his film, subverting expectations here and there. All he saw Star Wars as being was the plot of the originals. He had no vision, imagination or scope beyond it. He didn't care for the story JJ was telling or the story of the trilogy. He also didn't care about the story to follow.
With this insular deconstructed view, he lost sight of characters like Luke. Seeing them only as the mentor role and serving his Star Wars story. Not continuing the larger story of who they are. What is going on in the larger plot. Characters like Finn and Leia which have no analogue in the originals have nothing to do. Finn's arc is a retread. Leia sleeps for most of the movie. Poes is about a take on a type of hero character. DJ was a take on Han Solo, but without a good heart.
He has to force a connection between Rey and Ben. Do the throne room, but the bad guy wasn't redeemed. It's different!
The film ends, and all you're left with is still the basic premise of originals. With no story. He abandoned JJ's. Retread the backbone of the original, set basically nothing up. Just Rebels vs Empire now. Except he didn't understand what Star Wars was, deconstructed it and lost its elements. Fans revolted. When the filmmakers don't care about the story, why should the audience?
He simple was not interested in continuing the story and there was a story in The Force Awakens. The film didn't explore a lot of depth or world building but if anything that gave the next write even more freedom. Rian's film was simply not about being anything other than his take on Star Wars.