Operate on this:So you're saying that we need (and have to pay for) let's say 10 exits and 10 flight attendants whether we have 10 passengers or 100? You're common sense seems to be inoperative.
If the fuselage as designed, has HOLES for x number of plugs/doors, then it should be doors--period. Otherwise, don't design it so the number of doors can be changed. Make them fixed. If the plane was designed to have 6 doors, then 6 doors it is, not 4 and 2 plugs, for example.