I think Rey can still want revenge against Palpatine without her parents needing to be noble. Firstly, they were still her parents, and despite the level of abuse/neglect implied by literally selling her into slavery, she’d still probably be opposed to them being murdered, especially since she doesn’t remember them well enough to harbour any personal grudge. Secondly, he’s Palpatine: he’s responsible for a huge amount of death, for turning Ben and starting the First Order (and thus getting Han, Luke and Leia killed), and is actively trying to kill the rest of her friends. Difficult guy to not want some kind of revenge on.
My ideal Rey Palpatine version of this movie keeps her parents as bad people and tries to shift more of the plot onto her worrying about being evil because of using the Dark Side all the time and being tempted to join with Kylo Ren, rather than some kind of genetic determinism. But that’s a looooot of very fiddling dialogue reworking. There’s a lot of tough points, like “why would Rey’s parents not give up her location to Ochi if they were drunks who sold her and not lovely self-sacrificing heroes”, and what to do with Luke going on about “Because you’re a Palpatine!” on Ahch-To, etc.