Airlines need to give more straight answers. The delay was in fact ATC. I completely understand that the delay was not their fault, but they shouldn't quote a delay unless they are pretty darn sure that it will take that long. Otherwise there is no use telling pax that there is a delay.... and neither the information online or over the phone tells you what the delay is for so you can't expect the pax to know that an ATC delay is very contingent on many things.

One way an airline can minimize the inconvenience of a delay is to keep pax from waiting around a gate endlessly because they won't give proper information. If it looks like there might be a delay give the pax an ontime departure time followed by the words "Delay likely" and if they are sure the delay will occur, give us a new time and let us wander or come to the airport later.