Truthfully it flabbergasts me that console gamers are so steadfast in their need for an optical drive. On PC, most of us gave them up 10 years ago, and the world didn't end. People bitch that inferior consoles hold back what PC's are capable of, but then also bitch when consoles try to adopt some of the ideas that make PCs superior. I stand by it, I'd much rather see a sleeker, cooler, more reliable game system that isn't held back by decades old technology.
A. Console gamers don't get an equivalent of "Steam sales". MS or Sony will "discount" digital games on their respective stores here and there or limited times, but used disc games are, on the whole way cheaper. As much as I HATE GameStop, they are one of the few forces keeping console game costs down at all. Remove discs altogether, and you'll likely be charged the full 60 (which, for digital, makes no sense in the 1st place) on 5 year old games, because, whatcha gonna do about it?
B. Media playback.
C. Places, as few and far between, where reliable broadband isn't available. This is less and less the case, but is still a reality.