I’m all for unique and different and subversive, but not at the complete disregard of established character.
It’s not so much that Luke changed: change is obviously part of character development and characters can grow and evolve; it’s kind of the point of any story, really. It’s that it was such a dichotomic(lol) change to the very fundamental core of the character brought on by something offscreen, seen only in flashback in a weird almost downplayed way that we have no emotional connection to.
Luke is the guy who reached into the darkness to pull out the Dark Lord of the Sith despite more powerful and knowledgeable people telling him that it was impossible (that is why they failed), so I just don’t buy that he’d abandon the galaxy to burn while he went off to die alone.
I don’t want him to be the “perfect old Jedi who exiled himself to learn the bestest powers" either; I didn’t really want him to be wearing prequel robes sitting at the head of the New Jedi Order like in the books or something. I was hyped to learn that he was in exile and that he wanted the Jedi to end (why? what happened? what could cause this? Luke wanted to be a Jedi like his father more than anything!), and I didn’t need him to be off learning “Force Nuclear Bomb” or something to defeat the enemy. I was even mostly down with his overall reasons for abandoning the ideals of the Jedi Order! Aside from the hopeless nihilistic angle, I felt like it totally fit my feeling that Luke had transcended the failings of the old Jedi Order.
I would have been content with a simple “I realized I was unable to stop the First Order by myself and I would have been hunted and killed had I remained in the galaxy, so I came out here to wait for someone worthy who could take on the task.” That feels like Luke to me, not “my apprentice went bad and even though I’ve personally dealt with almost that exact situation before and prevailed, I decided to give up on everything and run off to die.” Even Obi-Wan didn’t give up hope when literally everything he had ever known was destroyed by his brother in arms and closest friend; he went off and bode his time until he could send Luke out into the galaxy, and through Luke’s redemption of Vader we know that Obi-Wan wasn’t half the Jedi Luke was.
You could even do it the way it was in the film but actually make us care about the Luke/Ben relationship and actually show us why Ben’s fall shook Luke effing Skywalker so hard that he was willing to abandon the galaxy to burn. The way it is presented to us is just… prequel-level garbage. Did Luke even ever like Ben? What was the nature of their relationship? Was Ben a good likeable kid? Who knows. If Adam Driver wasn’t so great in the role, the character would just be Anakin Skywalker 2.
I didn’t feel cheated, I just felt like I wasn’t watching Star Wars or the character I love. I think that’s the biggest crime of TLJ. It’s so damn frustrating because I went in wanting to love the movie, I wasn’t sitting around for months before release analyzing all the trailers and all the lines and coming up with theories; I went in clean with only what I knew of what came before before and an open mind and left wondering if I had even seen a Star Wars film.