Want to Fly? It's Time to Pay By the Pound

I like this idea from Samoa Air, which will set airline ticket prices according to weight:

Proclaiming the "pay only for what you weigh" scheme, the company's website says: "Booking a flight with us is as easy as inputting your approximate weight into our online booking engine (don't worry, we will weigh you again at the airport) – you then can prepay your 'guesstimate', guaranteeing you that much weight is allocated to you for that flight … with Samoa Air, you are the master of how much (or little!) your air ticket will cost." ...

Samoa Air's chief executive, Chris Langton, said charging by weight was the fairest method. "People have always travelled on the basis of their seat but, as many airline operators know, airlines don't run on seats; they run on weight and particularly the smaller the aircraft you are in the less variance you can accept in terms of the difference in weight between passengers," he told ABC News.

Only question: do fat passengers, by paying based on weight, get a bigger share of the plane? And if I want more space, can I pay for another 50 pounds or so and get a bigger seat?