I don't need another popcorn bucket, but if they let me refill my Tie Fighter bucket or the popcorn buckets I got from Tokyo Disney, I would gladly pay $1.
Six Flags does this. We bought a popcorn bucket for $6 or $7 and can refill it for $1 all year long. We just bring a few dollars each time we go and it's the only snack we buy at Six Flags. It'll be interesting to see if Disney makes this a more permanent feature. Of course at Disney there are so many good snacks to try...