My take is that if you grew up loving young Luke and imagining what grown-up Luke would be like, you probably had this image of him that was sure to be shattered. And that was very intentional on the filmmakers’ part. But as you say he came back and kicked a** at the end so I really loved him having an actual arc instead of being a wooden guru with nothing to do.
I agree the Canto Bight stuff is the weakest part of the movie, but I was so focused on Rey/Kylo/Luke that I didn’t have time to care about the minor quibbles I had. I came out of the theater completely satisfied. It was crazy for me to see all the “discourse” in the fandom afterward.