I loved the movie overall, and I think most of its flaws are relatively minor stuff that could be fixed or mitigated with light cuts, but I have VERY mixed feelings about its handling of Luke. The way he died – a display of the Force that was incredibly powerful yet epitomized “knowledge and defense” rather than attack, followed by peacefully disappearing while gazing on a twin sunset – was brilliant and perfect…except for the timing. Luke restoring the Jedi Order was one of the only specific bits of unfinished business the OT gives the main heroes, so to kick that can down the road to Rey’s generation just feels wrong.
So that’s the one thing I’d most like to see addressed by a fan-edit not beholden to official canon – whether by rearranging things in a set of Sequel Trilogy edits, moving Luke’s death to IX, simply cutting Luke’s fadeaway & the “he’s gone, I felt it” lines, removing the glow effect from Episode IX Luke, etc. But I don’t think it’s worth attempting until we know what Episode IX gives us to work with in terms of both Luke material and whether we see more Jedi begin to be trained at any point.
I also think there’s a decent chance of Abrams course-correcting in IX with substantial use of Luke as a Force Ghost (though there’s obviously only so much that can be done now that he’s dead), and there’s some indication he had a somewhat different motive for Luke’s exile in mind – TFA ends with him in full Jedi robes (which, okay, could simply be Rule of Cool), but he has no reason to be wearing them most of the time under Johnson’s characterization, so much so that changing clothes is one of the first things Luke does. Besides, it’s one thing to want to go into hiding, and another thing to specifically do so at the site of the universe’s oldest Jedi Temple. I bet Abrams and Kasdan’s original idea was that Luke sought it out not because he wanted to end the Order, but that he was looking for some sort of long-lost Force knowledge that could give him some new insight into the dark side and turn Ben back…but never found it.
But again, it all depends on what material Episode IX gives fan editors to work with.