A Mary Sue doesn’t cease to be a Mary Sue just 'cause she has ubermensch genes.
Yeah, but it helps. I guess it comes down to what one wishes to preserve most in the canon. Like I said, I hate the genetic thing and have hated it since the ridiculous Leia retcon in ROTJ. But I dislike the ‘no training required’ thing of the ST even more, because it takes away from Luke’s arc and struggles. I’d rather roll with a version of Force genetics (I find a Sith version of this at least mysterious enough to carry some weight) to justify Rey’s power levels than go with RJ’s random ‘X-Men Force powers’ thing.