Without getting into a line by line debate, I really don’t think you “get what RJ was trying to do” if you insist in the next breath that it’s “stupid.” It’s not how you wanted the story to go, and that’s fine, but those emotions are clouding your judgment if you think it’s “stupid” or “bad storytelling.” The writing was all there even if it wasn’t the story you wanted to see told.
This. Luke went on a quest to find the first Jedi temple. He left R2 a map to where he was going and found it. Something after getting there, reading whatever sacred texts he found, meditating and ruminating on his failure, led him to stay. He didn’t set out to hide, but rightly or wrongly, from his point of view he saw that (to paraphrase what someone else said) training new Force users on the light side always had the potential to end up with them on the dark. This, as you’ll recall is the reasoning behind Yoda not wanting Anakin trained to begin with. Luke took it a step further and reasoned against clinging to the belief that only a renewed Jedi Order could preserve the light:
“And this is the lesson. That Force does not belong to the Jedi. To say that if the Jedi die, the light dies, is vanity. Can you feel that?”
I also think it’s getting overlooked that Luke did train Rey. Reluctantly at first, after sussing her out, but it didn’t take until Yoda and the last act of TLJ for him to come around. He was hesitant for good reason; if you think about how she was drawn to the dark, and how her innate power (spare me all that “Mary Sue” BS) on the level of Kylo Ren scared Luke of her going dark in a way he wish he had been scared of for Ben before the fall of the temple. Taken as a whole with TRoS, can you still blame him?
What kept him from coming with Rey on the Falcon included the correct notion that him going out there with a lightsaber to take on the whole First Order wasn’t going to accomplish anything. Maybe if he hadn’t cut himself off from the Force; if he had straightened what had really happened at the Temple out with Ben, things could have been different, but that ship had sailed before Rey came to the island holding a lightsaber in TFA. The “legend” could have come back, but not in enough time to save the day, and he recognized that. What he ended up doing by Force projection accomplished more for the cause than he could have by getting on the Falcon.
Remember the themes of the movie, “the greatest teacher, failure is” and how they’ll win by “not fighting what we hate, but saving what we love.” Individual character arcs in TLJ didn’t occur in isolation. It was one thematic story that resonated as a whole. What Yoda said applied to Finn, Rose, and Poe too, and what Rose said applied to Rey, Luke, and Leia. And, especially with regards to ReyLo (my wife prefers “Bey”), they carried into TRoS too.