The following contains spoilers for Star Wars: The Last Jedi
Mark Hamill has made no secret of the fact that he wasn't entirely sold on the version of Luke Skywalker that Rian Johnson created for Star Wars: The Last Jedi. Now that the movie is out, Hamill is speaking in more detail about exactly what the issue was. It appears that Hamill just doesn't believe that the Luke Skywalker that he knew from the original trilogy would have reacted to the situation that way. He feels that Luke would have done more to try and fix his mistake, rather than hiding out on a distant planet. According to Hamill...
I said to Rian, 'Jedi's don't give up.' I mean, even if he had a problem, he would maybe take a year to try and regroup. But if he made a mistake, he would try and right that wrong.
Of course, Mark Hamill also understood that Star Wars: The Last Jedi wasn't a story about Luke Skywalker. It's a story about other characters and in order for the story to take them to the right place, Luke Skywalker needed to be something different than what Hamill thought he should be. The actor draws a line between what he calls the George Lucas version of the character, which is the one he describes here to Jar Jar Abrams, and the new version created in the post-Lucas era.
While fans can (and will) argue until they're blue in the face about whether this version of Luke Skywalker is appropriate. It feels like it should be pointed out that whether or not Luke would handle this situation in that way, Jedi absolutely do give up. Both Obi-Wan and Yoda go into hiding following the prequel trilogy, just as Luke did, and do little to nothing to deal with the Dark Side force user they helped to create, however accidentally.
Even after filming Star Wars: The Last Jedi, Mark Hamill still hasn't come to terms entirely with this version of the character. He says that while he believes the character he played in the film does serve the story well, it's still not the version of Luke that he considers to be his.
This is the next generation of Star Wars, so I almost had to think of Luke as another character. Maybe he's Jake Skywalker. He's not my Luke Skywalker, but I had to do what Rian wanted me to do because it serves the story well.
While Luke's choices here may not have been the ones Mark Hamill thinks the character should have made, in the end, Hamill points out that it's "only a movie" and he still hopes people like it. Many do, although the reception among fans has been mixed. One thing is for sure, we'll be talking about Luke Skywalker a lot over the coming weeks and months.