it's impossible for every criptic employee to work on this at the same time. It's not to hard to appoint someone and say go talk to the community, or go inform the community whats going on.
Now, from a professional standpoint I know that it's not the smart thing to do, but I understand why Cryptic would avoid the forums for a while. You see, during one of the Betas (I can't remember which) there was one sorry sack of excrement who actually tried to pick a fight with a dev because said forum poster claimed the developer was "wrong" about how the game worked.
Considering that is but one of a handful of instances where the community has taken dumps on the Cryptic employees, I can see why they'd rather not deal with the forums. Trying to make any announcements regarding down time or the reasons thereof would be as effective as ****ing into the wind.