The thing of it is, the āNot my Luke!ā criticisms leveled against TLJ never made much sense to me because the Luke we get in that movie is so recognizable to me as the Luke of the Original Trilogy.
At his worst, Luke in the OT is impulsive, arrogant, quick to anger and slow to come down from it. When discouraged, he becomes pessimistic and defeatist. When we see him overcoming these character flaws in ROTJ, it does not mean that these flaws no longer live inside of him; it means that he is choosing not to give them the power required to rule his actions and dominate his decision-making.
But a moment of triumph is just that: a moment. You have to live your whole life making sure that you donāt let the worst angels of your nature guide your decision-making, and no one is perfect. No one can always make decisions that arenāt guided by their own character flaws.
It was to my mind entirely plausible that after years of being able to sense Palpatineās efforts to wear down child Benās resistance and, most likely years of Palpatine probably subtly influencing him as well, that Luke, known to be dangerously impulsive, might one night impulsively decide to take drastic measures to prevent āthe next Darth Vader,ā only to snap out of it once he was actually standing over his sleeping nephew and think to himself āWhat am I doing, this is crazy, heās just a kid, he hasnāt even done anything and Iām going to kill him because: what? I think he has rancid vibes?ā
And it was also entirely plausible that after everything heād tried to accomplish comprehensively blew up in his face, that Luke would throw his hands up in the air, throw in the towel and say āI give up.ā He had by that point devoted a significant portion of his life to trying to rebuild the Jedi Order, and the end result was that every last bit of work he had engaged in for the past fifteen odd years was reduced to ash and rubble. And he thought that it was his own nephew who had done it, to boot, thought that he had succeeded in creating the monster he feared would arise (Forever salty that Benās background as revealed in The Rise of Kylo Ren, in that he didnāt destroy Lukeās Temple, didnāt kill anyone who died that night, and didnāt truly fall to the Dark Side until years later was not at least touched upon in the movies but was instead relegated to a tie-in comic that a lot of movie-watchers will never read).
I think even people who do not become pessimistic and defeatist when discouraged would struggle to come back from that, would struggle to move on. I can see how Luke came to the conclusion that he had just been carrying on bad traditions, that it was all rotten to the core and none of it was worth salvaging, because heād tried to make it better and look what happened! And then he needed a good hard jolt, a good hard paradigm shift to get him to see the brighter side of things again, just like he did in the OT.
Yeah, that was very much my Luke.