If the pilots are not busy then there's no reason why they can't make a quick PA and in most situations this is the case. Sometimes however they can be very busy on the phone to op's, ATC, handling agents etc devising contingencies or what not and so this PA maybe delegated to the CM/purser. Indeed, a good CM/purser will offer to make it if he/she sees how busy the guys in ye flightdeck are. Quite often it isn't anything too technical and the information can be relayed by most senior cabin crew in an effective and credible manner, after all it's probably a delay that they have experienced before. But, like I say, a PA from te Captain never hurts. Then again most pax don't care who makes the PA aslong as they are furnished with the info.
At my airline extended delay information is given to pax every 20 mins regardless of whether the Captain has made a PA or not.
Last edited by easyflyer83; 8th September 2013 at 10:09.