It might make the the pax feel better but it won't keep them alive. Making a PA during an emergency descent is a secondary consideration to correctly executing the descent procedure and getting revised clearance from ATC etc. The tech crew would have been very busy indeed. Cabin crew cannot use the PA during an emergency descent because they are on oxygen too and could pass out if they took their masks off. Some aircraft automatically play recorded announcements over the PA system during an emergency descent. One I've heard goes along the lines of 'this is an emergency announcement, the aircraft is being descended to a lower altitude .... ' Would possibly help your anxiety but who knows.