Yeah, the whole LAN thing. Linked an article earlier in the thread that gives a really compelling argument, imo, that the online-only thing has precisely jack and shit to do with preventing piracy, and absolutely everything to do with exercising control over how legitimate users play the game. They're seeing how far they can shove draconian DRM into the single-player portion of their game (which is what a constant connection is, in respect to offline play), and that's really all that's happening.
Bliz (and others, this is becoming somewhat of a trend) are citing piracy as blatant misdirection, because it's a lot harder to argue against (Oh, you want us to be stolen from? How's that work, exactly?) and sounds like a good reason to implement that sort of control.
That constant-connection sort of thing makes good sense in online multiplayer games (Never trust the client!), especially where there's a PvP component, but for singleplayer? It's hard to see how one can't be wanting to call bullshit on that part. A notable amount of people are, but it doesn't bother a lot of others. I'm one of the former, myself, having a fairly spotty internet connection and abso-frakking-lutely refusing to play any singleplayer game that requires an internet connection to play, on general principle. I don't mind added functionality when connected -- that's actually pretty nice, a roguelike I play fairly regularly does that -- but requiring it for gameplay that has absolutely no interaction with other people (and thus no need to police for hacks, etc.) is simple BS and nothing else, s'far as I'm concerned.
The reason I (and others, really) care is, yanno', not that I don't or wouldn't enjoy D3 (I probably would, and it's the successor to one of the most commercially successful roguelike derivatives, which significantly interests me.), but because I can't, because someone, somewhere, wants to squeeze more pennies out of competitive multiplayer or some gimmick auction house I'll never use, and is willing to screw over the (now nonexistent!) offline portion in order to do it.
But hey, maybe we'll get really lucky. Bliz turned back from that completely flipping stupid "Use your real name" thing. Maybe they'll leave a offline option for singleplayer. It'd be nice. Not gonna' happen, but hey, hope springs eternal.