Actually, it sounds like you'll have lots of choice - perhaps not right away, but pretty quickly over time. There's nothing that says that RFID chip has to be in a wristband form factor. That's just the "default." They've already talked about people being able to purchase "fashion" MagicBands. And there's lots of talk about other likely form factors - wristwatches, lanyards, etc.
The wristbands are coming first, most likely because they're easy to standardize and harder to lose/misplace than a lanyard. But I expect that the other options will surface fairly quickly - if there's money to be made at it, Disney has proven quite talented at capitalizing on it.
These wristbands are NOT going to be like the ones for kids on
DCL or at Great Wolf Lodge, which can't be taken off. They WANT people to be able to take them off, so that they can pay for the "better" ones (early promotional pictures already show a kid wearing a MagicBand in a Pirates design).