Quote from Fitsu
But I don't get the negative, i'm not saying use mods to keep it alive but simply as an additional feature. If you or anyone can give me an example of how having a single player mode could lead to the potential hacking of multiplier because I don't see how it does. All of the files are already out there, hackers have access to local files and have read them all they simply don't have the ability to put them together and make the game work as it should.
Why would it be overrun by mods? Just like Diablo 2 the separate closed B.Net of the game would remain the clean version that Blizzard intended whilst the offline mode is the modders area and both can live together there's no need to pick one or the other. There is only ONE reason for always online, and that is money it's DRM to prevent people from illegally obtaining the game if you can give me one other reason with some actual proof behind it i'm all ears but all I see now is claims simply arn't true.
I don't know the internal workings of the game, but my guess would be it's similar to how WoW is setup in that the majority of files are stored locally, but you play the game while accessed to a server that limits the use of those files. Any changes made before connecting to the server are controlled by the program checking them before accessing the server and rectifying any issues. However, it's safe to assume that it's much more advanced than this because I don't believe there's anywhere you can actually access all the required files, specifically the server files. If this were the case we'd fully capable private servers of the game available, like with WoW. If I'm wrong though please correct me. But, I don't think it's just a case of "they can't figure it out".
WoW is also a great example of this getting out of hand, as there are various hacking incidents that happen in it routinely and effect gameplay at times. For example, I recall a potential hack of being able to clone specific items. FPS are also plagued with hacks as well. So just because there aren't notable instances recorded of a game like Diablo 3- keep in mind a lot of hacks aren't reported by companies - doesn't mean it doesn't, or couldn't, happen.
Lastly, nothing you've said has proven that the game needs an offline version. Blizzard has their reasons, and while money may very well be a part of it you can't simply chalk it up to just that when you don't know their actual reasons. You're speculating, not stating facts. The only viable argument against it has been the Hardcore issues for people in remote regions. Modding isn't necessarily a viable argument against it, because while it is beneficial it's not a negative thing for a game to lack modding, especially when a game has developers dedicated to it for it's longevity.