I think Ben needs to survive. He feels really out of place as a force ghost, and the movie makes it clear that Leia only stopped training because her son would die if she continued.
Except he still died, so what was the point of her not being a Jedi?!?
Ben dying makes Leia’s storyline even worse in TRoS. Cut his death.
I felt exactly the same, hence why that is now part of my main storyline. I felt a lot of people forgot about Leias vision.