Disney has never been good about cleaning their databases. I still get emails to my email address, addressed to a nephew that went on a trip nearly 10 years ago. At the time, he was a minor and appeared fourth on the reservations.
I would never associate a payment card with a myDisney+ account. I just don't want the Russians, Chechens, and Chinese - Dark Internet to have access to my stuff.
The FP+ system should be better in the long run for me. I don't like paying, right now, for a system where I am the beta tester. They physically removed the old system way before the new system was debugged.
I don't like the fact that their myDisneyExperience app has access to my phone camera, phone calls, (to whom I am calling), network communications, my GPS location and my battery/shutdown functions. What are they going to do, take video in my room while I am getting dressed? Why do they need to know who I am calling, when it's likely Disney web support anyway?
It's the creepy factor, not whether or not FP+ is a better system. I am very likely to have the app uninstalled most of the time. Disney stop being creepy!