I cannot imagine the usefulness of such an item. You had to grind to get the tokens to be in the BOTMC so why would you want to send in an angry letter cancelling it? Unless of course, youre in some wacky cult that dislikes alcohol.
I think it may have been in a discussion on Wowhead or Blizzard Watch, but one person said that it was a relief because they'd get multiple Brewfest letters spamming his/her inbox and he/she was tired of handling it. (I guess Blizzard can't be bothered to fix that bug. Some players have complained about it for years.)