But few want to pay more for leg room. It's just not much of a benefit compared to the five things I mentioned (and several others like comfortable lounges at hubs -- but not apparently decent food). The airlines want to sell leg room because it's very easy to adjust.
Not that it's on the way to many other countries...
There are no other flights directly between Asia and Latin America (unless you count the EK GRU-DXB flight), though NH may be flying to MEX soon.
Basically, the problem seems to be that the USA does not have "sterile transit"; if your plane stops there in the way to somewhere else, you have to disembark and go through customs, and you need an expensive visa.
On my most recent trip to the US I selected cities that I could get between via train to avoid the entire mess apart from arrival into the US (and made an effort to depart out of Canada).
Among a wide variety of industries, a large portion of revenues come from "upsales", pushing some impulse buys extra like insurance. Which is to say that the impulse buy extras are shitty ripoffs and consumers over time have grown to expect promises to be worthless and to only pay for things they can clearly verify.
And that relates to selling cellphone with longer battery life - all the companies make unrealistic claims, how could someone feel safe giving up something that can see (like a feature or a smaller size) for something they can't see?
I think the airline market hardly ever offers real choices and many things that look like choices end up actually being the same flight sold by different carriers from the same alliance. Alliances are a huge pet peeve of mine anyways. There are certain (US based) airlines I strongly dislike and would like to avoid. However, it's almost impossible. Even if I book another carrier the flight often times end up being operated by them again. Sometimes it gets changed after I book. This is a dysfunctional market. I want Delta and United out of business and I've had the same from others. Yet we are all stuck flying them because we can't avoid it.
Want +3in legroom? For each flight, go to a flight forum and punch in the route to figure out what plane they're flying. Google the airline and that plane to figure out how much legroom is available.
Give up and just fly jetblue and/or southwest, and if they don't go, decline to travel.
1. Flightaware
2. Seatguru
3...
4. Comfortable flying
(Step 3 is becoming a millionaire that flies business class.)