While I do agree with the game needing more than this; I think a system like this will enable the game to seem more enjoyable, or rather; lessen the wait and give players something to partake in while waiting for content to arrive. When you mention Immersion, what you say is true; however I often find myself removed from the Immersion of MMOs purely because of the Players, and Tasks that are performed. The only time I feel truly immersed in an MMO is when I'm involved in a heavy Story-Content Mission. There is also no reason that the Development Team can't tie lore into the Achievement System.