I don't know your situation, but I'm really talking about the people who are so overweight they have to keep the armrest up to squeeze into the seat (ie. spilling into bordering seats). I was being a bit facetious about the "60% of americans" bit. If a passenger pays for a seat and he/she forgoes part of the seat due to said reason, should no compensation be provided? Also in these circumstances there seems to be a safety issue in the event of emergency evacuation.
At least these were my thoughts on a recent flight this week as I was literally pushed up against the window.