What I meant is that Johnson was left with very little wiggle room when it comes to "wtf happened to Luke?".
He went from being a galactic hero in Ep. VI to being a goddamn hermit on a random ass planet.
So Abrams dropped that bomb and passed it onto whoever would carry on with the sequels, with zero explanation as to how exactly Luke ended up like that. People were mad at Johnson because "how could Luke possibly do that?!" but he pretty much was forced into that position by Abrams.
Same for "wtf happened to the Republic!", "who the fuck is Snoke?!?", "how did Solo go from a war hero who cared about all this after initially being only interested in getting paid, to getting back to his shitty smuggler job?!?" etc, etc, etc...
Abrams dropped all this shit as established facts beginning the new trilogy, leaving whoever would come next to direct Ep.VIII to deal with explaining all that shit.
Coruscant was fine, the super-duper-mega death star blew up the "Hosnian system" which was apparently the new home of the galactic republic, with the main planet being Coruscant 2.0 (both in terms of function but also visually).
Because reasons, I guess.
Being perfectly fair with Abrams and his stupid Mistery Box stuff. all this plot points could have been explained with cliche tropes at second film. Of course, is still scummy because JJ Abrams leaves the job of explaining shit to another guy.
Rian Johnson cardinal sin was trying to subvert the expectations and not playing ball. I feel he did a Knights of the Old Republic II, making Star Wars media for people that dont like Star Wars media. This is fine when is not on the flagship stuff but in the main films it feels like he just wanted to see If could get away with some stuff, making a film he wanted to make but not what the fans or Disney wanted. (Disney mismagement is another can of worms)
Luke is hiding because is trying to fight Snoke in his own way (ancient Jedi artifact, hiding his biological son/daughter, meditation), Snoke is an ancient Sith Lord or another form of force users, Rey is someone important daughter or is a reincarnation of the force like Anakin, etc. All of this could have been better explinations. Cliche but better than: "lol no we were no setting anything. Pay me."
Abrams set up was lame and directionless, but RJ decision of "fuck it lets not even try to follow up" created the dissonance.
Disney and Lucasfilm mismagement were, at the end, the ones that fucked up. Abrams going to Abrams and Rian Johnson decided to not even try to play ball, Disney and Lucasfilm were the ones that decided this was okay until Solo bombed hard.
I mean sure, you could always find something here and there, but the sheer amount and scope of the stuff that was introduced, either with radical changes to the state of the galaxy, main characters, and out of nowhere "what in the fuck?" new things was just stupid.
Every single major character was unrecognizable. You have some serious 'splaining to do if you want to now tell people that Luke is a grumpy hobo hermit, Han said fuck it all and went back to his shady shitty job, Leia returned to being at the head of a small band of merry resistance folks fighting with scraps.
The Republic is basically non-existent, and it's like the Empire was never defeated. There's a new big bad guy who's quite clearly at the very least on par with Palpatine in terms of power and influence.
They somehow have a fucking goddamn PLANET turned into a mega death star-like weapon.
There's a new Luke 2.0 who's somehow super strong with force powers, lectures Solo about his own goddam ship, is the best goddamn pilot the galaxy has ever seen, etc.
Abrams came up with all this shit and went "there you go guys, you can deal with explaining all that crap yourselves I'm out lolz".
Like, where the fuck do you even start when you've been handed this.