Ugh. I'm 6'3", and I only squeeze so far when surrounded by a couple of overweight people who don't know how to tuck their elbows in. Losing 1" of width doesn't sound like much, but it will make those awkward flights a little more common and a little more awkward.
I'm 5'4" and I hate people who don't tuck their elbows in. But even worse: fatties who want the arm-rest up so that you can subsidize their air travel. (They want to be able to leak over into your seat.) Yes, I fly a lot, and yes, this happens.
I've experienced the request to raise the arm rest. So far I've been able to say no and make it stick.
In theory people who take up more than one seat are supposed to get charged for more than one seat. However this rule is not that well enforced because of how much outrage people have over being told to pay extra because of their weight. (A condition which most people have little control over. Read The End of Overeating for the biochemistry behind how the modern food industry induces overeating.)
Personally I would be in favour of a surcharge on anyone who significantly inconveniences their seatmate, with a fraction of said surcharge paid directly to the inconvenienced fellow passenger. I think that this would increase politeness, and where it doesn't, the financial bonus would reduce my frustration level.
You know the Israeli day care center study, where parents who were fined for picking their kids up later were more inclined to be late, because they perceived the fine as a fee-for-service? I think that formalizing the overweight-versus-space-donor relationship would lead to even more antagonism, on the same theory: "What are you looking it? You're getting paid good money to be sat on, shut up, I don't need to cooperate with you."
I do know that study. The problem that study found is that the price they put on being late was below the social stigma.
The solution is to make the price above the social stigma.
I think a reasonable rate would be $100 fines, to be handed out no more often than once every 10 minutes, half of which goes to the afflicted seatmate. If you are in the space of seatmates on both sides, you pay the fine once per afflicted seat mate. If you need to move to avoid continued paying of the fine, then you owe the airline for a second seat.
This is on top of the social stigma of having had people come, and explain how you're breaking the rules in front of the rest of the plane.
At that rate, a person who can't fit in a normal seat will see buying 2 seats for their cross-country flight as the cheap option. And one who isn't comfortable sitting in one may think extra hard about remaining uncomfortable rather than inconveniencing someone else.
