Agreed. It seems Disney approached this like it was the NBA All Star game. Just bring in a bunch of big names and let them "do their thing" without a whole heck of a lot of preparation. They weren't looking at this from a team approach, where they had a defined objective and knew the end game. They should have agreed on how it ends - and have a few ideas of how they were going to get there - before even putting ink-to-paper.
Although TFA was a reboot, it set a few characters up very nicely - to be evolved/developed for the remaining 2 films.
But the biggest blunder Johnson made in character evolution/development IMO, was with The Knights of Ren. TKR could (should) have been epic. And Johnson just ignores them?
We are of the same mind here.
I see what you are saying about the Knights of Ren. That is one of dozens of examples of things which were set up and then either subverted or abandoned by Johnson. The thing is, that a lot of really good movies (including the original trilogy) do this at times because of editing or tweaks to the story, so when we point these specific examples out (like the Knights), people will respond that its no big deal. But I think the point is that in this case, it is a symptom of a disease, rather than the rare exception it is in other good movies that abandon certain plot lines.
And yeah, TFA was a reboot, but I didn't mind that (sounds like you didn't either). After all, WW2 was a sort of reboot of WW1, so we can suspend disbelief with TFA. And it seemed obvious after TFA that the next one would not need to be as rebooty, and I was genuinely excited to see where they took the new characters... to see what plot arc Disney had in mind. Because, you know... obviously there is a general arc to something that is announced ahead of time as a trilogy.
Instead, we got a game of Mad Libs or telephone, or choose your own adventure, where the story is handed off to Johnson and treated as if it can go anywhere without regard to any fixed landmarks of previously established character traits or theming.
There are dozens of forgivable things in TLJ... if taken separately:
-Luke retreating to an Island to take a break from the force.
-Reys parents being drunks and subverting the setup about her lineage in TFA.
-Knights of Ren AWOL
-Canto bight
-Rose Teco
-the "save the horse-donkeys" instead of slaves, and instead of actually completing the mission.
-Luke chucking the lightsaber over his shoulder (played for cheap laughs)
-Luke almost murdering a child in his sleep
-hyperspace ramming
-lazers bending in space
-Lame slo-mo ship chase with gaping plot holes (gee I wonder if they are trying to sneak onto that planet that they are flying directly towards)
-Luke having doubts about the goodness of the Jedi
-Space Witch Leia
-Killing off Akbar without comment
-Tone deaf yo-mamma jokes making Hux look very un-scary, and played for very cheap laughs.
-The movie-long berating and humiliation of a character (Poe) who was set up as a hero in the previous movie, again done for some cheap points of some sort.
-The first movie in the saga to not have a single lightsaber duel
-Killing off Luke without letting him at least have a battle.
-Killing off Snoke with zero explaination
-many, many more
Take any 2 or 3 of these and surround them with good plot, characters whose actions make sense, good drama, good action, and an overall continuity with the Force Awakens, and you have a good movie. Put them all together and you have a disaster.