Usually game developers do fill up quite a large space that they don't need.
It is to give the piracy group a struggle to rip it and upload it.
Of course, the space they fill up, they just use "dummy" files, and most of the time the pirates do remove them. It just hinders the process of getting "0-day" launches.
Once a new technology starts rolling, if you're not part of the steamroller, you're part of the road.