Well, in the official statements Microsoft said because of the feedback from the community. I have to admit despite not taking part in the vast majority of gamers, I am pleased to hear that there is no connectivity and no issues with lending/sharing games. (I still was set on buying it before this announcement, not going to lie)
One huge thing I noticed: You have a choice between discs and Xbox Live, from day 1. We're given the option to go full digital or retail if we choose. I like that development, although it seems sharing would be difficult with a digital copy.
EDIT: One huge thing: No region lock. All countries can play.