I don't think the amount is as high as you think it is. Also I would hate for everything to go DD; I don't know about everyone else but my ISP gives me a cap every month. 100GB!! I have to share that with everything in my home. Online gaming, Netflix, Youtube, downloading and whatever else my wife and child use on a daily basis (computer, phones, tablet, console, roku etc etc).
So if a game is a 9GB download for a DD title I can do about 2 of those a month before I;m going to have to curb some other internet usage. Plus whatever the cloud is going to use and I'm going to start getting letters from my ISP or have my speed reduced or account canceled. This also doesn't help people who cannot get good speeds through the internet. I think most of us take for granted that A LOT of people have crappy internet and can't download games.
Heck where I live if you don't live in town you either have dial up or satellite, guess my buddy just won't be able to buy games anymore!