If my flight's delayed, I appreciate being given a reasonable amount of information on whether it's a technical issue, crew availability, ATC problem, etc, so that I can make an informed judgement on how long it's likely to last (because the airline often won't stick their neck out and tell me).
That includes being told that a late incoming aircraft is the reason - at least in that case I can be reasonably sure that we're going to depart as soon as the aircraft can be turned round.