...and the weird thing is, I think with some tweaks, Old Man Luke could have worked. Por ejemplo: Rather than tossing his father's light saber over his shoulder, what if Luke had intensely stared at it, then pensively closed his eyes as he handed it back to Rey: "This is yours, now. This no longer belongs to me." as he walked away. Showing regret, grief, and resignation to his fate without dishonoring the legacy and import of the Skywalker saber.
My assumption was that Luke had gone looking for some ancient Jedi wisdom at the first Jedi temple after his failing with Ben Solo. But finding no solace, no answers in the long abandoned temple, he felt that he must "disconnect" from the Force, to prevent Ben/Kylo and Snoke from sensing Luke's presence on Ach-too and seeking him out and "forcing" another confrontation.
You know: Since Force Ghost Luke knew that Rey was a Palpatine, then how MUCH MORE did he know? Was Luke aware of Snoke at any point in Kylo's fall to the Dark Side? Did Luke only get that nugget after he joined the Force? Or did he sense it after he re-connected with the Force, and decide to fight Kylo in the holodeck? If so, then Luke may have know that Snoke was an imperfect clone that Palpatine tried to imbue with his presence, but failed (in the same way that Obi-Wan knew Vader was Luke's father, but withheld the information).
The below video gives a considered explanation of why RJs Luke Skywalker simply was NOT Luke Skywalker, how his character was destroyed. It's a couple of minutes but well worth the watch. I skipped ahead to the important part(s) RE: Luke's character.