You do make a good point.
I disagree.
What happened to Obi-Wan and Yoda:
- Jedi purge aided by Obi-Wan’s former apprentice now Darth Vader
- Galactic Empire takes over the galaxy
- Yoda and Obi-Wan face off against Sidious and Vader despite terrible odds
- Yoda fights Sidious to a stalemate and is forced to flee, as troops arrive
- Obi-Wan defeats Vader, leaving him for dead
- Obi-Wan and Yoda are now hunted by the Empire, branded traitors with the approval of the Senate, and are forced into hiding
- Obi-Wan and Yoda hide Luke and Leia
- It takes twenty years for the Rebel Alliance to become a significant threat to the Empire’s powerbase
- Leia asks Obi-Wan for help in their most desparate hour, Obi-Wan answers their call
What happened to Luke:
- Luke’s Jedi Academy is destroyed by his former apprentice partly caused by Luke’s unfortunate mistake
- New Republic controls most of the galaxy
- FO is growing in power, but at this point still a fringe government
- Despite the fact that there’s still plenty of opportunity to stop the FO with the help of the Resistance and the Republic fleet, Luke doesn’t even try, and goes into exile, leaving everything behind
- In Luke’s absence the FO grows in power to the point, that it is able to destroy the Republic capital and take over the galaxy
- Luke refuses to help even after his sister Leia through Rey informs him of their situation, and his best friend has been murdered
Except let’s look at what is going on in each instance. In the PT (or even the OT backstory prior to the PT), the Empire has taken over, the Jedi have been hunted down. Ben and Yoda are in hiding. Waiting for something. They have hope that something will change.
Luke has just had his entire new order of Jedi wiped out (either killed or turned to the dark side). We don’t really know how many, but it wasn’t a lot. The facility is wiped out and the leader is none other than his own nephew. He fears that if he trains anyone else, the same thing will happen again. And Snoke and the Knights of Ren make a force that he does not have the power to combat. He would not kill his father in ROTJ so I’m sure he would not kill his nephew.
So the situations are vastly different in terms of what is at stake personally. Also remember, that Ben and Yoda were fully trained Jedi masters. They had learned to put their emotions behind them. When did Luke learn that lesson. We see in ROTJ that he is still prone to letting his emotions take control. He uses that to defeat Vader. As Johnson writes the lines for Luke to speak, he is also addressing fans who have idolized Luke and made him into something that the movies don’t show. The movies never show him attaining true Jedi mastery of his emotions and feelings. And the events that led to his self imposed exile in the ST are ones that, given the character traits shown and mentioned in the OT, would lead him to do exactly what he did. Luke was never perfect, only very determined. He used the Jedi training he had been taught and it failed his padawans. The same way it failed Kenobi in training Anakin. Luke sees that failing but does not know how to correct it. I saw it quite clearly in the PT that Lucas was showing that it wasn’t Kenobi or Yoda who failed, but the Jedi teachings. We are back to that. The Old Republic Jedi order had a major flaw - they didn’t teach their padawan how to avoid the temptation of the dark side. They just said don’t start down that path. They had gotten to a point where they denied attachments because it might lead that way instead of teaching how to avoid and resist the temptation. It is like teaching abstinence instead contraception to avoid teen pregnancies. It doesn’t work. Both Ben Solo and Anakin needed teachings that the Jedi didn’t have and that Luke doesn’t have.
Luke had three choices after Kylo turned. He could go after Kylo Ren and defeat him and the other dark ones. He could build a new order of Jedi to combat them - but the conflict would come eventually and there was no certainty that the new students wouldn’t be cut down or turned like the previous batch. Or he could decide not to kill and go into hiding. Staying and helping Leia really wasn’t an option because Snoke was already there and he would be expected to train new Jedi. And that is what he now fears. Luke rightly sees the Jedi order as flawed. He has given up instead of finding a way to fix it. And if you go back and watch the original, what he did is exactly in keeping with his character traits as established in the OT.