Snarkiness aside, this actually reduces what Disney can collect. The Magic Bands have two sets of antennas inside them: One is a near-field chip that you have to tap against something to make it work, just like how Apple Pay does, or the plastic cards that you can request from Disney if you don't want to use a Magic Band. That's what this new feature replaces.
Magic Bands also have a battery powered antenna in them that works like the EZPass toll transponder in your car which enables Disney to automatically capture ride photos for a coaster train full of guests, display your name within ride special effects, or (probably) whatever other crowd tracking Disney does to see where people go throughout the day. The Apple Watch doesn't have this feature, so the Mouse wouldn't be able to track you if you used this exclusively.