I have constantly had the feeling that most wanted to see the hero Luke at it again rather than a mentor Luke. But the mentor has to move out of the way for the new hero, in this case Rey.
I see this claim made frequently, but haven’t actually witnessed any sequel critics mention that they expected—or even wanted—Luke to be swashbuckling. Obi-Wan didn’t when he was the aging mentor; he had one final confrontation with his former protégé in order to buy his companions time to escape…which is exactly what Luke did in TLJ.
I’ve seen some griping about that confrontation not being in person, and therefore not a real physical fight, though. I’ll admit I would’ve been more satisfied with a closer parallel to the Vader-Kenobi duel that incorporated some lightsaber action, but I don’t dislike what Johnson came up with.
The real criticism I see again and again is that Rey never needed a mentor to begin with due to her emergent Force powers and Luke completely disregarded his responsibilities as a Jedi until Rey kindly reminded him what they were.