Don't make the mistake of thinking that the members of this forum are a reflection of the standard passenger. Most, though not all, on here have worked in the industry and have a good understanding of far more than your average passenger, even regular flyers. The most important piece of information you can give passengers on a delayed flight is the new departure time. For the majority of passengers the reason can be as simple as 'a slight tech problem that won't take long to fix' to 'Our engineers will need x minutes/hours to rectify the problem'.
'Operational reasons' is a bit too vague and when possible some fill in information should be provided, but I have known occasions when the full explanation was so long winded that the passengers would probably have fallen asleep by the time you'd finished, and many still wouldn't have understood why there was a delay.
On one flight delayed by weather, heavy snowfall, I was called down to talk to a gentleman wearing a dog collar who was haranguing the check-in staff and demanding to know exactly when the weather was going to clear and the flight depart. All explanations that we could only give estimates based on information received from the Met Office fell on deaf ears. Eventually I took him to one side and very politely asked him if he could perhaps use his connections to the big boss and let us know the answer.
Guesstimating weather delays was always fun, especially when asked 'When will the fog clear'