You don't own anything but "time". You are paying for the privelege of "time at Disney" in a more comfortable apartment setting. Its the way of all time shares.
Certainly not all time shares. My family actually owns five weeks in assorted time shares. We will always have the right to use a specific room at a specific time. They are deeded just like your own home is. There is no expiration date. The majority of time shares are still like that, but with the success of Disney, more are trying the "time" offering. All we have to pay is maintenace every year. Disney really the first to be successful at the "time" thing. DVC has to pay maintence on something you don't own. It is like if you had to pay taxes on Expedition Everest just because you entered the park.