I don't think a lawyer would accept a case like that on a contingency basis. If you sue Blizzard because they closed your bnet account the best you could hope for is to get the account reinstated. To get anything else you would need to prove damages. Either is unlikely because a judge would probably dismiss the case before you finished explaining what you were suing for. And then your lawyer walks away with a percentage of the zero dollars you "won." I can't imagine that there's a lawyer out there who would go through the trouble of starting a class action to get a bunch of gamers their WOW back, for the same reason.
On the other hand, I am sure that there are plenty of lawyers willing to charge a person $400 to write an angry letter to Blizzard on their behalf and another $400 to write a letter back telling them that Blizzard refused to restore the account.
That said, the CYA language in those TOS agreements really shouldn't be allowed, even if it is just an access agreement for a video game. "You agree that we can do whatever we want, for whatever reason we want"? Who do they think they are, the NFL?
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