After I had my "Wow that's cool!" thought one of my next thoughts was "What will the cost be to ship that box to each family?" It kind of circles around to my other thought though. If it costs $10 to ship the box (which I am guessing is high) but allows a guest to skip the check-in process then it could, in theory, save money/time for the resort by having fewer guests checking in regularly and recouping the cost that way.
Keep in mind that Disney is in the money making business. They wouldn't roll out something like this without a way to make a profit in the long run. If it makes things more efficient and thereby gets more people into the parks then that is more people spending money. Time is money, especially at Disney so any way they can streamline things and get you into the parks, restaurants and stores and less time waiting for things is to their benefit as much as it is yours.
Again, thinking about DME and arriving/departing. You have your MagicBand and you approach the bus, wave your band and boom, the driver knows which resort you are at or which airline you are going to, how many people are with you, etc. With that information in a computer a driver could, in theory, have his route adjusted for him to be the most efficient based on who his passengers are. Faster trip to your resort or the airport, fewer stops, etc.
There is a lot of good that could come out of it with the right amount of imagination.