I think a more apt analogy would be those hand trucks that come on U-Hauls, where it's already physically on the truck, but just sealed up unless you pay a little extra.

So if you don't buy the option it's not destroyed forever, but can be utilized by future users once you move on. This allows them to provide customers with instant access to extra value by charging them enough to support putting a sealed hand truck on every U-Haul, or extra terabytes in every account.