I get what you are saying with what do you do with Luke after the TFA nonsense. The point is it never should have gotten there. That's why the entirity of the sequels are hot garbage.
Luke leaving his friends in ROTJ is not even close to the same thing. He left because he was a literal homing beacon that Vader and Palps could sense. That was Luke's reasoning. Not that it mattered because Palps knew what was happening with their mission anyways. Being a monk type character was the old Jedi mindset. In a way it gave way to Anakin becoming Vader. Yoda warned Luke of this with his attachments to his friends. Saw what it did to Anakin with Padme. But Luke fought through that and came out with a new understanding of how the Jedi could evolve. Attachments are not a hinderance and can be a strength.
The sequels totally erase all that with the garbage they put out. It's just bad. Palpatine coming back makes Anakin's sacrfice meaningless. It's like the OG movies don't matter at all.