Josh Mosqueira has explained that Blizzard and Sony identified the significant amount of consoles not connected to the internet as their reasoning for including offline play in Diablo 3.
via N4G: pc news feed http://n4g.com/news/1216880/diablo-3-lead-designer-explains-console-offline-mode-delivers-inadvertent-pop-at-next-gen-xbox
via N4G: pc news feed http://n4g.com/news/1216880/diablo-3-lead-designer-explains-console-offline-mode-delivers-inadvertent-pop-at-next-gen-xbox