I disagree, I thought it sold his POV really well. His “solution” to the problem is a bad one, but it’s bad in very understandable ways. When you unfairly come down on yourself, hard, for not living up to ideals you keep pushing out of reach for yourself, you’ll make punitive decisions that are less about making amends and more about getting the hell out of the way, because you honestly believe, at that point, that’s the best option. Just leave. Everyone else is better off without you, because all you do is mess things up for everyone you love. Depression is a liar, it’s said. He’s acting the way he’s acting in no small part because he probably knows in some place what he’s doing is the wrong thing, but he can’t see how anything else could possibly work. The judgment you’re casting is exactly the judgment he’s already applied to himself. He’s being selfish and petulant. But that’s also a part of who he is, and you can struggle to overcome those aspects of yourself, but most people never truly eradicate them. They’ve got to work to keep them at bay, all the time.
I get the feeling behind “But Luke Skywalker shouldn’t have to keep failing in order to be interesting” or even more simply “I don’t WANT Luke Skywalker to fail anymore.” I absolutely understand that emotion behind the complaints. Nobody wants to see their hero succumb to depression and spiral out into self-loathing and self-destruction, right? Nobody wants their friend to cop out. But Luke doesn’t get to be that trapped in amber happily-ever-after hero once the decision is made to make Episodes 7, 8, and 9. And my counter to “I don’t want Luke to fail anymore” is that Luke Skywalker’s victories are as satisfying as they are BECAUSE he fails at first. And fails again! The best he’s ever been as a character is when he’s struggling to overcome his own self-doubts about what is possible, and whether or not he can do it. Luke is at his best as a character, and as a key component of Star Wars storytelling, when he’s in a low place, and through his goodness, his will, and his sense of right and wrong, he not only gets out of that low place, he finds himself standing in a much higher one, and he brought his friends with him, too.
The Last Jedi does that for him. You can be mad at him (or mad at the people who wrote him) for making him un-perfect as a means to move the story forward, but I’m not mad at Luke, or the people who remembered how interesting and relatable and INSPIRING he is when you trip him up and bring him low. I’m empathetic towards him. I’m sympathetic, and I’m pulling for him to realize he’s made bad decisions, even if it takes Yoda showing up and zapping a tree to finally get the light to spark in his eyes. I want my friend to get it, and I’m relieved and happy when he does, because I know what he can do when he finally gets it, and it’s something to see.