Dining options when you first board?

Think the motivation to steer people away from the MDR is so it is not overwhelmed. Couple that with most people's excitement to be on the ship they may not have patience to sit through lunch. Buffet can handle the mob a lot easier.

I also think the MDR is not fully staffed, because some of that staff are helping load/deliver the luggage on embarkation day.

The cruise company is looking out for itself. By encouraging people to go to the buffet, they make use of the most efficient (for them) way to feed a large mass of people with the least amount of staff. They also know that there are a small amount of people who don't want the buffet and prefer the MDR experience. So they open one and staff it lightly to satisfy those people.

As for VIP dining - they know exactly how many people they are going to serve and are staffed to handle it. They also want to be able to put faces to names for later in the week and show you what a great perk dining there is :D

Maybe it's psychological profiling. Those brave few that insist on going to the MDR will be counted on to lead groups of people to the life boats in case something happens to the ship.

Goodness! I hope that doesn't mean I have to stop drinking during the muster drill?!?