You can say it doesn’t necessarily contradict TLJ, but it was totally unnecessary, in my opinion.

Your answer is beautifully thought out, but I guarantee you that Abrams nor Terrio took the time to rationalize their choice as much as you have.

I think they made Rey a Palpatine for a few reasons.

To give fanboys a reason why Rey was so powerful.
To give her a personal reason to hate Palpatine.
To mirror Luke’s own connection to Vader, creating another needless parallel to the OT.

Again, you can rationalize it, but there was no legitimate reason for them to go back on Rey’s parents being bad people that didn’t care about her. Even you’ve admitted that could’ve been handled better. For Abrams and Terrio to say they actually did love her, and abandoned her for a reason? And they sold her to Unkar Plutt, of all people? They couldn’t have thought of a dozen other safer places to take her? It is just ridiculous, and treats the audience with no respect. To totally go back on what the previous movie established.

Her being a Palpatine, in my subjective opinion, is just so much less interesting than what TLJ on its own set up. Giving Rey this answer makes her path so much clearer. Everything you said about her character arc could have easily been accomplished without her being a Palpatine, and been less muddled. But I guess the only way Rey could be that powerful is if her power came from a man…

I’m glad you’re getting something good out of this movie. You’re clearly a intelligent person. I just hate that you’ve probably put more thought into this idea than I think the actual filmmakers did.