Why then do you have to download every game even if you have the disk?
It downloads the entire game for each disk game you put in, seems to me that the could've found a more efficient way to actually do that since you know both the 360 and the XboxOne support installing games from disk so they got the ability to create a disk image.
If all they needed to download is an emulator and a compatibility config file that would've been a much smaller download package..