I work for a web host (not this one). From my experience, this is generally what is going on during downtime (note: times are BEST CASE scenario):
T0: Servers go down T5-15: Someone realizes something is broken. T15-45: Initial someone calls another someone to tell them it's broken because the night guy probably can't fix it all by himself. T60-70: All the engineers are woken up and know OF the problem. T90: Engineers figure out WHAT the problem is. T120: Engineers fix problems. T150: More problems arise. T180: All problems are solved, no more customers are mad.
Moral of the Story: As you can see, it already is a very involved process to get servers running again. Now, as a customer, you want an email to notify you that services are down. First, the admin needs to find out exactly which customers are affected and then write up a nice happy email to you letting you know we're working on it. Do you want a happy email or do you want your servers fixed? Your call. Downtime is chaos. Do not ask to be notified of chaos.