This is where the case for Luke in TLJ breaks down for me. That his legacy was enacted behind closed doors made no difference to the universe of The Force Awakens, wherein every character’s motivation was dictated by a quest to find Luke, specifically because of the actions he committed to 30 years prior. Rejection of his legendary status would be much more plausible had it been an overexaggerated or a falsified one.
But it’s Luke doing the rejecting of his legendary status, not the universe. It’s a question of Luke never quite believing in himself, and even when he did, he did it the wrong way. He is being ruthless towards himself in that confession to Rey, and it shows that he never quite believed in himself the way others did, and when he tried to, he did it with reservations and a lack of conviction.
That’s very much in character for Luke Skywalker. “Always with you, it can not be done.” That’s the part of the legend Luke sees that nobody else in the larger universe has ever even heard of, and that’s the part that scares him the most, and haunts him the hardest. The Last Jedi is a movie that is consistently about discovering who you REALLY are, and the only way you can do that is when you are brought low by your biggest fear, and you decide you have to move beyond it. HOW you do that is what defines you. That happens with Poe, it happens with Finn, it happens with Rey, it happens with Kylo, and it happens with Luke.
That’s what I meant by rejection, that he rejects it at all is confusing. You cite a criticism from Yoda in Empire to explain his lack of resolve, as if the following film didn’t go to great lengths to demonstrate that Luke had grown beyond that. He became less of a doubter than the master who once called him the same, when he thought he could redeem a murderer through love for his father alone, and succeeded in doing so. For what reason would he have to doubt himself at that point? For what reason is there to parse from the remainder of that film that he’d remain a doubter? It’s less a character assassination than it is a character regression; that you have to compare TLJ Luke to ESB Luke is telling of exactly what’s wrong with the writing.