It would be crazy to actually update every single game's score over time as more things are added. The problem being that (save for these online issues) scores would only go up as things are patched. And I don't think a 8.0 game's scores deserve to go up just because they implemented some additional content. Fixing all the "problems" with your game and giving us more random content does not make your game eventually deserve a 9 or a 10.
A game should get an initial score uninfluenced by any future developments. Any DLC should be scored separately, free or paid.
In this case where they could not know about the server problems until launch I don't know what to say. I'm alright with them lowering the score temporarily in order to encourage a swift remedy, but I think this could just be done by putting a temporary big disclaimer at the top of the review about the game's current broken state.