I was the one that suggested making Rey a new chosen one over on the Rey Nobody thread, I think it covers all the issues Neverar outlined:
Making that list of plot and theme issues, here are the major ones as I see it:
1: Rey needs some inner darkness, whether that be from early life experience or from an ‘evil’ bloodline.
2: Rey needs a reason to have been left on Jakku, living next to several plot-important ships/places.
3: Rey needs a reason that choosing the Skywalker family name is important to her.
4: There should be a reason that Palpatine in particular is a fitting nemesis for Rey.
5: There should be a reason why a Jedi Hunter would wish to find Rey as a child.
With this revelation Rey would essentially be a new Anakin, with the same potential to fall and plunge the universe into darkness like Vader did. It also gives her another reason for choosing the Skywalker name, as it belonged to her previous incarnation. It makes sense Palpatine would consider her a nemesis and would try to hunt her down. In this version of events, Rey’s conception would be a vergence in the Force, a direct result of Palpatine cheating death and undoing the destruction of the Sith. As for point 2, this reveal doesn’t require an explanation for Rey to be on Jakku, she’s the daughter of junk traders who lived on a random junkyard planet, and that’d be the end of it.
I agree with RogueLeader’s take that we shouldn’t be focusing on Rey’s backstory and making things more convoluted, this reveal would put less emphasis on Rey’s past, it doesn’t matter where she comes from or who she used to be, which is the heart of TLJ’s reveal. As Maz puts it: “The belonging you seek is not behind you, it is ahead”. Instead of threading over the same ground TLJ covered, we’re adding a new dimension to Rey’s character that is more relevant to her present and future, as heir to the Jedi or heir to the Sith. This movie is already bringing back Palpatine as the big bad guy, so it makes sense to bring back the chosen one as well and bring things full circle.
I had a hard time thinking how this could be implemented, since it’d be awkward for Kylo to reveal this and their dyad connection at the same time, but I hadn’t thought about just outright exising the term dyad. I think this would work even better with this reveal, since their connection is apparent without the need for a specific term, they’re both related to Anakin, one through spirit and one through blood.