I'm a big fan of Blizzard titles (but then, who isn't?). My friends and I still get together on at least a monthly basis to play Starcraft or War3 on a LAN. Given that, it should be no surprise that I think this is a very bad move by Blizzard. There's no way my friend's place is going to get an internet connection that is capable of handling all of us simultaneously, with latency comparable to a LAN.
If they keep on this path, Starcraft2 will be largely irrelevant as far as I'm concerned. I doubt it will have the staying power of Starcraft 1 simply because you can't play a pick-up game with friends. Yes, I'll probably still get it eventually for the single-player and occasion B.net game, but you can bet that the pirated version cracked to include a B.net clone for LAN is looking mighty good in comparison.
While we don't yet know what "super" features B.net 2.0 is going to have that are supposed to make up for LAN play, it has been confirmed that B.net play will be free for Starcraft 2 purchasers. However, rumors are starting to fly that B.net will not be free for Diablo3. The statement that SC2 play will be free was carefully worded, and Blizzard responses on D3 have evasive, but with not re-assuring implications.
Given that Diablo3 also has been confirmed to lack LAN play, the only way to play multiplayer is via B.net. If the rumors are true, then the only way to get D3 multiplayer is to pay for it. This is a total reverse from the old days of "spawned" copies of Blizzard games where you could have several players all using the same copy of the game.
I think the removal of LAN play signals the decline of Blizzard as a long-term game maker. Which is too bad as they have wonderful legacy support. SC2 and D3 will still sell like crazy I'm sure, but 10 years from now we'll probably still be playing Starcraft 1 at LAN parties. That or some enterprising pirate will save the day.
Anyway, there's a petition to include LAN play, not that it will do much good. Doesn't hurt to try.