There's two parts to Bluray: the storage medium and the specification for the data on the storage medium. You can burn and read bluray disks with a filesystem,

There's two parts to Bluray: the storage medium and the specification for the data on the storage medium. You can burn and read bluray disks with a filesystem, and presumably you could use your bluray reader with those kinds of disks. People who don't want to use their bluray reader to watch DRM-encumbered media don't want to pay for a licensed device.