I'm sure those that signed off on this investment believe the payoff will come from two places. 1. new and returning guests who see the value in the system (a small portion of the payoff) and 2. the INFORMATION they gather from those that use it.
Think about a company like Facebook. Why are they so valuable right now? Because of the information they are gathering about people, their habits, their likes, their dislikes, their brands, their networks, their friends, etc.. As soon as I heard they were using this to track your purchases, I knew that the information was the key to this program.
Believe it or not (and I personally think it's not as valuable as those selling it would have you believe) but information about consumers is the most valuable commodity in the business world right now. Companies are spending big bucks on analytics to try and better identify their customers and deliver them targeted messages. Think about all those coupons that print out at the checkout at Target,
Walmart or your local grocery. Those are not random coupons. Those companies spent millions of dollars on software to track and analyze your purchases to deliver those coupons to you.
Disney is no doubt doing the same thing. I'm sure they believe this system will ultimately give them information they need to better target potential guests with offers that they just can't refuse - why ? Because they know exactly what offer to make. As quikah said, it's a whole new revenue stream.
Just my two cents.
Personally, as a gadget / tech geek, I can't wait to try it out.