[Hammer]

I'm also split on this issue...

If the seating area was a reasonable amount, and you're STILL too big, then you should have to pay for 2 seats. Let's face it, there's A LOT of really obese people in this country, and when it comes down to it, the cost of the flight comes down to weight and space. That's how airlines\transport companies price shipping for everything else.... how much weight you carry determines to some extent how much fuel you need and the package sizes may determine what kind of aircraft you can use, etc... etc...
Have you ever seen those boxes in which your carry-on has to fit before you can put it on the plane?
There's a reason for that....

The other side of the coin is this:
I'm a small guy, and sitting in coach is just about the most uncomfortable 2 hours I can think of. If I feel confined, I couldn't imagine how a regular to large (but not obese) person might feel.

If the seats were a bit bigger, I wouldn't have any opposition to the "mandatory purchase" rule...