I don’t see how Rey overcoming family dark side baggage is any different than Luke doing the same. Especially redundant because that’s part of the reason why we are to believe that Ben is Kylo (the Vader in him).
Rey Nobody is compelling because she is forced to determine her own path. It’s uncharted territory which is what makes it so interesting. Kylo/Ben is a compelling character because he has always struggled with the pull between the light and dark. Vader was an inherently different character because he was pure evil before his son managed to pull him back. There were a number of different ways they could have taken either of their stories (and how they’re intertwined) but the result they came up with is purely unimaginative, plain and simple. There is more to characters, their journeys, and their choices than just what “team” they’re on.
The idea of her being Nobody is compelling but does it make for a good movie? If I play out that scenario to it’s conclusion what do we have? She decides to be good or evil based on…what exactly? With a natural proclivity to be evil supposedly I see it as more heroic or meaningful that she decides to kill Palpartine…now, if she decides to be evil without that…now that would be interesting.