LOL. This is a good point. The current pricing is so variable on when and how you buy your ticket through souped up computer modeling. A 300 lb person buying a ticket in February would probably pay the same as a 90 lb person buying a ticket in March for an April flight. It would be nonsensical to do weight based pricing. I can kind of see doing a surcharge for total package (person plus luggage) in excess of some threshold, but that is about as far as I think the airlines can take it.