I remember having this same conversation a while back. The problem with making her parents bad people is that the Palpy/Rey scene at the end relies on the whole “she will take her revenge!” spiel. He’s trying to get her to hate him. But if Palpatine is responsible for the killing of her parents, and they were bad people, then really Rey should be thanking Palps for neutralizing those scum bags. Not exactly the greatest strategy. And don’t even get me started on the fact that it makes no sense that they wouldn’t reveal her location to Ochi if they were bad.

Don’t get me wrong, it would have been better for them to be bad, but unfortunately the movie we have been given relies on them being good. Doing the opposite would involve removing way too much content and make the Rey/Palpatine scene kinda confusing.