I’m fairly certain aspects of the story were developed with the story group (and quite likely the TFA writing team), but there’s nothing wrong with Johnson going solo on writing duties. In fact, I think it will be interesting to see a singular vision in that regard.
I guess it’s possible, it would be interesting even if he just got to flesh out an existing plan for the narrative. But I’m just suspicious that this is all a Lucasfilm board room creation after the 2-3 named writers on TFA. It’s probably all just done with a committee.
“I am not a committee” - Rian Johnson, probably.
The story group is no committee. They’re just a group of people who love and know a lot of things about Star Wars and are trying to keep continuity within the universe.
I don’t think they were involved much beyond brainstorming and consultation. Even though JJ and co. set up an idea of where things would go, it seems like Johnson had a lot of freedom to decide what would happen (hence writing the treatment for IX and also giving small input on TFA).
And there’s nothing wrong with 2-3 credited writers on a film. Having a lot of people to bounce ideas around is a good thing. I get the fear of too many cooks but ultimately it came down to a team of just two writers calling the shots with JJ being the final arbiter. It’s clear how that situation broke down if you read the Art of TFA book or watch the interview they gave (at WGA I think). Basically Ardnt had been hired to write and they were developing with him, until it was decided JJ and Kasdan would write together. A completely organic creative process.
The idea people have in their mind of Disney execs focus grouping the most profitable ideas for the script and writing them down is just a complete fiction.