I mentioned in my Series of Thoughts on the Last Jedi the whole “Messiah Can Only Save You Once” aspect of the Hero. Robin Rowland does a more systematic Defense: connecting the tragic tales of King Arthur, Odysseus, Theseus, and others. In a nutshell, when the hero ages, the time of his glories pass, and the wearies of peace and the costs of past acts catch up to him.
So for the aging male hero (we’ll talk about Leia and females later) there are number of destinies (sometimes choices but often the rule of the Fates). The hero can, as Campbell observes, turn to the dark side and become an emperor and tyrant. Or the hero embraces the light side to become a saint, a sage, a world redeemer. The third choice is to choose or be fated to embark on a final journey, what Campbell calls the departure of the hero. That journey is not always pleasant or successful, but that last journey to departure is the story of Luke Skywalker in The Last Jedi.
I would add the story of Beowulf to this as well. After he kills Grendel and his mother, Beowulf returns home and rules his father’s people well and wisely for decades, until a dragon rises. Beowulf fights the dragon but is slain by it (a companion kills the dragon), and the land is left with no king (for some reason, Beowulf has no children). This mirrors Luke’s final act in the Last Jedi, dying into hope to give the Resistance a chance to escape. There is a piteousness Beowulf’s defeat, as there is a piteousness in Luke, a despair at ever overcoming the Darkness. And as with Beowulf, a companion must complete the hero’s task. Wiglaf, who kills the dragon, is something like Rey in this.
This doesn’t mean anything if your principle objection to The Last Jedi is the null plot lines or the shoed-in romance between Rose and Fin or the way Vice Admiral’s Holdo’s Clever Plan turns out to be the opposite of clever. But if your problem with it was that you don’t like to see Luke Skywalker reduced to a state of wretchedness and despair, then that’s something worth reconsidering.
In any case, Read the Whole Thing.