It isn't about cheating
The problem isn't about Blizzard wanting to crack down on cheating; that's acceptable on its own terms, even free games like MUDs or Quake servers will ban bot cheaters. The problem here is that DMCA is being used for things that it shouldn't be used, equating a simple "cheating tool" to a warez game-pirating cracker. This has bad implications on stuff not even related to "copyright infringement" or even "MMORPG cheating".
According to this ruling, if I type "there is no cow level" on StarCraft, I'm BREAKING TEH LAW.
If I use one of those "Diablo character editors" to give my sorceress an instant lvl 32, I'M BREAKING TEH LAW.
Hell, I'm probably violating the DMCA if I type IDSPISPOPD while playing DOOM. "Oh noes! He's walking through walls!"
Yes, cheating on MMOs is wrong, but the ruling in this case is also wrong. Two wrongs don't make a right.