Even George Lucas admitted that becoming a parent changed the way he made movies. You’re no longer a rebel fighting the system, but a responsible adult and a role model for your kids. I do not doubt that Hamill’s view of Luke is filtered through this lens. Who wants to be a parent who even for a moment contemplates the murder of a relative? Anyone would rightfully be uncomfortable with such an idea, so sometimes it takes an outsider to admit unsavory elements of a character that have always been there.