You must remember that DVC is a timeshare. That means you are buying "time" at a lodging place which just happens to be in Disney World. It is not a "prepaid vacation", but instead is pre-paid lodging. Meals, transportation, park admissions, etc, etc, etc, are not included. There are certainly "perks" that pertain to those activities (such as the $100 discount on annual passes), but those perks can and do change frequently.
Also, as with all timeshares, there is an annual "maintenance fee" to pay just like when you own a home or anyother real estate interest.