Well what occurs to me as a huge issue is for those folks who live far from the port and have already purchased their airfare. For example we have booked a Transatlantic for November. I am getting ready to purchase airfare at the moment and will probably spend close to $2000 just for airfare before it is all said and done. If they were to bump us off this cruise. We would be SOL.
Also for people who get one or two weeks of vacations yearly, sometimes they do not have the luxury of getting extra time off at a later date to take a cruise. If they are lucky enough to find a cruise going to their desired destinations out of the same port or nearby where they were originally sailing from on the same date, that would be great, but it's not too likely.
I do have to agree I prefer to cruise with a vast mix of people and would prefer not to be cruising with a huge group that has basically taken over the ship.