It does seem counterproductive to have more passengers, but less stands.
But there are a few things to consider.
- Airlines are now squeezing more seats into aircraft, I think BA and LH are in the region of CY168 on their A320s, which 10 years ago would have been something like CY150.
- More airlines are using larger aircraft too, the A321 seems much more popular thee days than the A320, for example, although the 757 is slowly dying a sad death, similarly the 738 is replacing 733s, even at easyJet the A320 is replacing A319s.
- Long haul is seeing a lot of growth, especially to the middle east. Emirates are using A380s and 77W, EY, SQ and CX are 77Ws, which are substantially bigger than A330/A340s.