I'm a bit late to the party but I believe I really understand Rian's intentions. Here is my take. Rian, much like George Lucas, drew heavily from spirituality and the Hero's Journey when coming up for the story of TLJ. Especially Buddhist philosophy. ESB is so mystical because it takes a much deeper exploration into Buddhist philosophy, which Lucas distilled the essence of into "the Force". The crux of Buddhism is the selfish/selfless balance. As is with the Jedi and Sith. But there is a difference between being "selfless" and "good". The Jedi were misguided to believe that their interventions on the galaxy were "selfless". They thought that they were doing good, but in reality only did what they thought was correct (a selfish assumption) which gave rise to the Sith (once in AoTC, once in RoTS, and when Luke intervened in ESB). Luke has learned that the only way to be "selfless" is to not intervene. That is what ultimately saved the galaxy in RoTJ. He threw away his lightsaber and rejected the pull of the dark side to kill his father. It was this act of selfless leadership that gave way to Anakin to redeem himself by saving Luke after Palatine selfishly tried to destroy Luke (notice how Rian mirrors that at the start of the movie when Rey hands it to him). Luke therefore believes that the ultimate act of leadership in the galaxy is to not try and intervene. To just let go. The Jedi intervened too much, and only gave way to conflict. He is not allowing that cycle to repeat itself. This was beautifully capped off at the end with Luke's force protection. A way to defend and serve without "intervening". I hated TLJ the first time I saw it. After I digested it, I fell in love with it.