Why did Luke disappear and go off to grow a beard on an island? And why is he talking about the Jedi ending in the latest trailer?
Reddit User DraftDraw thinks that Luke, like Qui-Gon, has realized that the traditional Jedi way of life is the thing that has to end, and he is on a journey to figure out a better way: “No more blindly following dogmas, just leaving life, at is fullest, not suppressing your feelings like the Jedi Order, but not letting them corrupt you, like the Sith.”
So, seeing TLJ teaser, we all got pretty surprised when Luke said “the Jedi have to end”. While it can be assumed he meant the extinction of any Jedi, I see it as another way – the Jedi ”Order” has to end. Their ideals, their way of life. Luke knows, through Obi-Wan, Yoda, and Anakin, that the Jedi fell, and fell because of their own arrogance to perceive things, to give up their ancient ways or had some dubious rules, in trade of becoming a sort of private army, of militarizing themselves, of banishing emotions.
Who else knew this, but was still a Jedi? Qui-Gon, who lived through the Living Force’s way. He knew the Jedi were distancing themselves from what really mattered, being involved in wars and politics, to a Republic that tore them apart and didn’t even care to them during Order 66 even after they served them for thousands of years. Qui-Gon didn’t allow zealotry to cloud his ways, and the Jedi were becoming a corrupt force, being even perceived as not that different from the Sith.
So, my theory is that Luke researched this, noticed it, and is seeking to do the same. No more blindly following dogmas, just leaving life, at is fullest, not suppressing your feelings like the Jedi Order, but not letting them corrupt you, like the Sith.