You can accomplish accountability by requiring a permanent UNCHANGEABLE alias that you can associate a SINGLE character to without requiring people to use their first and last name. Trolls would still be forced to ALWAYS use the same alias (without creating trial accounts or posting from multiple accounts, which will happen) and nobody will be required to use their first and last name. See? Problem solved. You're welcome.
Edit: Blizzard has announced a reversal of the policy. The link to the source article isn't active but more information is here: http://www.wow.com/2010/07/09/mike-morhaime-real-names-will-not-be-required-on-official-forum/
Thank you, Blizard, for listening to your customers.
Edit again: The link to the actual source post: http://forums.worldofwarcraft.com/thread.html?topicId=25968987278&sid=1