If this got whittled down to an account, linked to and accessed by an email address and/or mobile phone number, containing: name on room key for resort guests/as much of a name as an offsite guest wants to give up, park ticket, and reservations I think it would achieve the "positives" mostly set forth by Disney PR. Ease of use, unique interaction with characters and rides, Fastpass+, Spam offfers, ect. However, where do you make money with that? I don't know of any scientific study to cite, but I know it's a fact people who use credit cards spend more freely than those that don't. And your bracelet will basically be your Disney credit card. Now, I know that's what your room key is now, but a lot of people don't know/don't care enough about it. But now it will be mandated for everyone to have one, and it's use will be heavily encouraged. $$$$$$$$$
I think the "tracking" in the park thing is overblown. If Disney wanted to, they probably could easily mine that data much cheaper. Your park ticket is tracked directly to you, and put something in Fastpass machines to keep track of when a ticket is scanned. Put some ticket scan or something in at food places, and you easily have an estimate of where someone is 75% of the time in park. And honestly, you're on heavily monitored private property: there's no real hiding anyway. It's not like TDO is going to have a Control Center with a bunch of blinking red dots circling around park wall-sized park maps.