You can actually tie your room key/park ticket, better known as your "Keys to the Kingdom" to a real-life Visa Card. If you do this, you can leave your wallet in the room. Also, if you are on the dining plan, your Key to the Kingdom will have your dining points on it.
I know you are probably wondering what happens if you lose your key. This has happened to us before. You can go and get a new one pretty easily, but you need ID, so why not just carry around your wallet?