Once they are ready to roll it out officially, I would imagine that an opt-out option will appear. Though as stated, you can always change back over to the RFID cards, since you're that paranoid. Nothing is creepy about it in the slightest. You're at a theme park that is designed to give it's guests magical experiences, not your local grocery store.
And Disney couldn't care less about tracking you in particular. When you consider that, on average, 50,000 people visit the MK alone each day, and adding in all the attractions, shops, and restaurants where they may scan your MB, there are literally millions of data points just in this one park every single day. In all of WDW every day, there are several million, and in a years time, you are talking billions. Disney does not have the manpower to track one individual for even one day, much less for an entire visit. They want to know during 10am - 11am how many people went through Adventureland, and how many went into the queue for POTC, JC, etc. so that they can staff those areas appropriately. Nothing more. Nothing less. If you think anything else, you really must wear your tinfoil hat everywhere.
Oh, and you do know that there are literally hundreds of cameras at every theme park, and have been for years, watching you all of the time?