Earlier this week, the firm revealed that the dungeon crawler must be connected to the internet at all times, even for solo play.
Blizzard has since said it is "surprised" by the negative response from players and denied it was for digital rights management (DRM) reasons to defend against piracy.
"I'm actually kind of surprised in terms of there even being a question in today's age around online play and the requirement around that," vice president of online technologies Robert Bridenbecker told MTV Multiplayer.
"We've been doing online gameplay for 15 years now… and with World of Warcraft and our roots in Battle.net and now with Diablo 3, it really is just the nature of how things are going, the nature of the industry. When you look at everything you get by having that persistent connection on the servers, you cannot ignore the power and the draw of that.
"Internally I don't think [DRM] ever actually came up when we talked about how we want connections to operate. Things that came up were always around the feature-set, the sanctity of the actual game systems like your characters. You're guaranteeing that there are no hacks, no dupes."
Watch a cinematic trailer for Diablo III below:
Bridenbecker added: "All of these things were points of discussion, but the whole copy protection, piracy thing, that's not really entering into why we want to do it. I'm a huge purveyor of online sites and from my standpoint, I don't look at DRM solutions and go, 'Wow, those are awesome'.
"I look at those and say, 'Wow, those kind of suck'. But if there's a compelling reason for you to have that online connectivity that enhances the gameplay, that doesn't suck. That's awesome."
Diablo III will also feature an online auction house where players can trade items for real money.
The dungeon-crawling sequel will feature five character classes - the Barbarian, Witch Doctor, Wizard, Monk and Demon Hunter - and is to include vendors called Artisans.
Diablo III will have a beta sometime between now and November. It is scheduled for a 2011 release.