So you don't have to watch someone smoke a cigarette for hours
We already know that games will have to install themselves onto the Xbox One in order to create some weird and annoying "tied to one account" nonsense, but there is a shred of good news. On the Xbox One website, it mentions that the player can boot up the game immediately, even as it installs itself in the background, just like the PS4.
I find it a bit disgusting that playing a disc-based game immediately is now touted as a feature and needs to be mentioned. This is the world we are living in, folks.