Above all others, the mere reason that adding offline mode would worsen the technical support experience of 99% of gamer's who have the internet is a valid enough reason to justify it in my view.  

They have done offline mode in the past - They admitted it was something they regretted doing. Are we to assume they are lying to cover up a secret hidden agenda? - Probably involved world domination.

All these mentions of how Diablo 3 did it great - seem to be ignoring that it launched with online only. It was months, maybe a year or two before that changed - because it had features that required an online connection (auction house). The console version that had offline mode was (imho) largely ruined by having local saves (due to offline mode) because when you did fancy playing coop - it was filled with hackers.

I appreciate that it might suit some people to have an offline mode, but saying it'll make millions if offline vs failing because of being online is frankly ridiculous. If the game dies after a few years then sure, petition for an offline maintenance mode.

I have no problem with online only games because 99% of the games I play I play online.

Get a grip. They decided this a long, long time ago. You are of a very miniscule minority that will find this a problem. If it is a problem, you are free to go play anything else.

You can read here our official response about this topic: Regarding Offline Mode