Mark Hamill (Luke Skywalker) has gave explanation of what made him to return to the Star Wars franchise 30 years after he starred in the original Star Wars film trilogy:
A thing that felt maybe wrong about coming back was the fact that the original trilogy had a beginning, a middle and an end. But there’s two ways of looking at that. On the one hand, it had closure. But if you look at it another way, it’s the story of how Luke went from becoming a farm boy to a Jedi and then the story ends. It would be like telling the story of how James Bond got his license to kill and became 007, and the story ends.
[Luke being a different person in the new trilogy] is what really fascinated me. Between “Return of the Jedi” and “Force Awakens,” there’s just decades of history that’s unknown. So I was wondering how they’re going to handle all this. Now, obviously, with “Force Awakens,” J.J. (Abrams) had a full plate. It was inevitable that they would push me down the line. I was sorry I wasn’t able to work with any of the original actors again. But it’s not about us anymore. In this new one, I was saying to Rian Johnson: I need to know my backstory. It was kind of unclear. You read where he is now and what he’s doing now and sort of have to fill in the blanks for yourself. So I did do a backstory myself. It’s not about Luke anymore, so it’s not really important. But I had to make sense of it for myself. What Rian came up with, I was stunned.