I agree that Luke was the only good character in the sequel trilogy, but I do feel like they took his character too far. I’m not saying Luke isn’t allowed to make mistakes, but I don’t think Luke from ROTJ would go to die on an island the instant something bad happened. He always seemed more hopeful than Obi-Wan or Yoda. I enjoyed Luke’s character arc, but I found it hard to accept that this is the same Luke from the OT, and I understand the complaints of those who felt they ruined his character.
They also undid Luke’s arc of overcoming darkness in Return of the Jedi. That moment he considered the cold-blooded murder of a sleeping Ben Solo undermines the scene in Return of the Jedi where he realizes his mistake after attacking Vader, tosses his lightsaber forward, and promises he will never turn to the dark side, knowing that it isn’t the way of the Jedi, which showed that he has matured to better face and overcome darkness.
He redeemed his father and conquered the darkness, only to fall victim to it yet again?
You could easily look at his temptation as an ongoing struggle. It makes his character more human and hence more interesting in TLJ. Plus he didn’t do it, so I still don’t know why certain people get all bent out of shape about this. He’s not space-Jesus.