And we already know he didn't inspire his son to save the galaxy thanks to Rian Johnson, then what did he actually accomplish? Why does the scene where he comes back from the Dark Side mean anything?
share*sigh* By the time Rian Johnson got to the story Luke was already a total failure who allowed his goofball nephew to fall to the dark side, destroy his Jedi academy, murdering or recruiting all of his students, & assisting the rise of the First Order to reek havoc & destruction on the galaxy, leaving his friends, family and the Republic to deal with the mess he left behind. All while he went to go hide on a far away island. "But hey in my head canon I just assumed some simple yet elusive, "really good reason" would be easily pulled out of thin air to justify why he allowed all that to happen, doing nothing to stop it and went to go hide on an island for years. "
The thing is that many of us who saw TFA for the poorly written pile of garbage it was early on could see that all signs pointed heavily to Luke being the exact Luke we got in TLJ & said as much while most everyone else was still in denial. This is merely one example that is largely on Jar Jar, KK, & any other incompetents who had a hand in that awful clusterf*ck of a script that laid the groundwork for most everything wrong with this ST.
I agree that TFA left no other realistic/dramatically-acceptable version of Luke than we got in TLJ.
Maybe instead of bitter, he could have become so enlightened that he didn't care about either side, but that sounds boring.
However, I've read a couple of Quora posts about Luke that make a convincing case for Luke only ever "winning" when he refuses to fight. More specifically, he's learned that he loses when he takes action. In that light, his total withdrawal makes sense, not just from the New Republic and the Resistance, but from the Jedi code and the force itself.
I'll edit this answer if I find the argument again - the Quora poster made it more eloquently than I ever could.
I agree that TFA left no other realistic/dramatically-acceptable version of Luke than we got in TLJ.
I disagree. All TFA did was say Luke hid himself and left a map so he could be found.Nowhere does TFA say Luke left a map to be found. The movie says Luke disappeared looking for the last Jedi temple and Lor San Tekka found a clue to Luke's whereabouts (the map to said temple).
If Luke did not leave the map then why did R2D2 have the rest of it? You could say that the resistance had been gathering pieces all along except for 2 things: 1) R2 was in hibernation since Luke left so he was never 'awake' to add the pieces and 2) when the part of the map was revealed everyone reacted like they expected it to be the full map.
It is apparent, to me anyway, from this that Luke got the map to the temple and hid most of it in R2 and gave the 'missing' piece to Lor San Tekka. He did this because while he did not want to be followed he also knew that one day the resistance might need to find him.
As far as the film saying Luke "disappeared looking for the last Jedi temple", to all but perhaps those that NEEDED to know it was a better cover story for his disappearance.
R2 had the map in his memory from years before according to JJ. Luke didn't store it in R2.
“We had the idea about R2 plugging into the information base of the Death Star, and that’s how he was able to get the full map and find where the Jedi temples are,” Arndt said.
Abrams says he chose to spell this out indirectly in the movie because he didn’t want the story to get bogged down in “how s–t happened 30 years ago.”
“But the idea was that in that scene where R2 plugged in, he downloaded the archives of the Empire, which was referenced by Kylo Ren,” Abrams said. Thirty-eight years later, in both our own and galactic time, that data becomes useful in The Force Awakens when a new droid approaches the dormant R2.