Everything I've read about the MagicBands at Galactic Starcruiser indicates that they're an important part of the immersive / interactive experience. Every guest is issued a MagicBand that's exclusive to the Galactic Starcruiser resort. And that might also include tracking your merchandise purchases. That's one way for them to track your cabin number when you make a purchase in the resort store.
Excellent points.
I'm sure that is the ONLY way to make purchases from the gift shop and getting the alcoholic beverages (which aren't included) - as far as immersion goes, they don't want anyone taking out a wallet in the middle of the cruise.
They probably have you link your credit card ahead of time and if there is an option to specifically NOT link a credit card, they probably tell/warn you that "you won't be able to get alcoholic beverages and you won't be able to make purchases at the gift shop". Midway through the cruise if you change your mind, they will be more than happy to help you link up a card. Disney loves taking your $$$.
I'm sure it's the same reason why they are giving you iPhones to use as your Datapad instead of letting you use your own personal phone - because once personal phones come out, photography and video recording can't be controlled and apparently that's something else you agree to while on the cruise - no photography.
