The idea that you need a plan or roadmap before you start a trilogy is nonsense. Not to mention that the only Star Wars trilogy that had a plan and roadmap was the prequels, and they’re objectively worse than the sequels.
After what the Marvel movies had done (which are nowhere near perfect), I think there was an expectation that the sequel trilogy would have some sort of coherency and internal throughline. They would tell an over-arching story. That’s not what we got.
And I’m not sure the Prequels are worse than the Sequels. Each film in the Sequel trilogy overcorrected the previous movie, and that created a tonal and story whiplash that completely unbalanced all three films. Hell, The Force Awakens was simply a retread of the Original trilogy and it was horrible.