Putting in one's birthday is an option for the forum, but the forum is an seperate entity from the game. About a quarter of the people in the forum have a different name than their playing name, on top of that we are talking about a buff for each person's character. Some people have nearly 5 accounts a piece, that's really a lot of excessive buffs and extras being thrown around.
I just think we should be happy when we receive stuff from Neji when the system goes down for a long time, or when we reach donation goals. Figuring out ways to gain something for nothing won't be given.
Having people know your birthday is nice, the best gesture is when someone across the globe or nation says, "Happy Birthday" to you because they see your name on the forum birthday list.