So lets see the reasoning here:

A percentage of Americans keep getting fatter so the airlines should offer larger seats - and we all pay for it. I don't think so - if anything maybe the airlines should weigh you in and charge for every 10 pound over the normal weight. After all a 400 pound passenger uses more fuel than a 150 pound passenger.

I feel for those who are 6-5 and above as they are the ones who can't stretch their feet - I think the airlines do a pretty decent job of getting these passengers into bulkhead seats. As for those that are overweight - buy two seats or better yet get in shape.