Tiak had to be translated into English, Chinese, Japanese. The voice over actors don't just sit there waiting for new Aion content, they have to be booked, and I bet they don't book them untill the game is running well for weeks on the Korean servers first.
Internationalization of game content takes time, this is not news, been discussed by others before, why do you think after each patch some dialogs come up in Korean again? There is a lot to check in a game and stuff always gets missed. New gear, interface changes, they all have to be checked.
However, this outage is something very different, not just an internationalization issue.