I hope someday Lucas’s treatments do come out, I’d be curious. But knowing his past writing processes (on the OT and PT), it’s more likely than not that his treatments were pretty short and vague. More importantly, even if Lucas himself had made the films he would have certainly changed the story of his treatments significantly over the course of time. So the idea that they should have chained themselves to those treatments just because they had Lucas’s name on them is monumentally silly.

More importantly, the idea that evil will always return is “nihilistic” is ridiculous. It’s just factually true. The idea that evil can be defeated once and for all is pretty naive. It works for a fairy tale yes, but Star Wars has been becoming less and less a fairy tale with each new entry. The idea that evil will always return is sophisticated and nuanced (perhaps too much so for some viewers, which is why they ditched it in TROS), and the message that there will always be good to face that evil is anything but nihilistic. It’s the very heart of what Star Wars is - never ending hope in the face of potential despair.