And has been shown countless times before, this does not work with high profile titles. Emulators and loaders will be available within a week for SC2 and Diablo3 which will allow the game to function on LAN just as well as if it did support it.
And not to mention the pirated versions of the game will be packaged with these emulators/loaders, meaning that the pirates will get a more fully functional version of the game - thus the only people actually hurt by this decision is the actual legit customers.
You should never punish your legit customers due to piracy, nothing will stop piracy, especially of high profile titles. If anything it actually drives more people towards the pirated version of the game.
And thats a fair argument I won't try to go against. I generally agree with you, I think Blizzard and every other developer (who develops primarily on the PC platform), are searching for ways to fight thieves.
The average joe won't go steal a car, but they will a game. Why is that? It simply comes down to the fact that people think they can get away with it. Until that has a radical shift .. people are always going to push it as far as they can.
I'll even go as far to say that in 15-20 years the internet will be so locked down and restricted that children will read about the 'wild west' days, when people could get away with stealing games/movies/music. Until that day comes, publishers/developers are going to try new things to fight piracy and yes .... legit consumer will suffer from it.
The thing to remember is, that its not the developers fault. The blame is on solely on the pirates.