I understand that everyone pays their cash and everyone poops sitting down however what ever happened to courtesy? If you're a shorty and don't really need the legroom then why make the giants suffer? It's like the bus or train: I pay the same fare as everyone else but I'll still stand and let the senior citizens, women et al take a seat.
There's not a dignity, honour or common courtesy thing associated with giving up a seat for an elderly, woman et al in a bus or train compared with a "short" person giving up their exit row seat for a "tall" one. Until it becomes more of a social norm in a similar fashion or part of the honour code, you won't find that it happens. And until that change happens, it won't be considered (from a greater social point of view) that not giving up your seat for a "tall" person is discourteous.
Mind you, with all this paid exit row thing going around the world, it's a riot at the moment when people can sit in exit rows and yet be not up to the required standard (safety wise) to sit in it! What if a frail person sits in an exit row? Would a tall person be right to ask them to be displaced so they could sit there (which "violates" the elderly person rule)? After all, they may not be able to comply with the safety requirements of the exit row (e.g. help with an emergency, lift and dispose a door which is 22 lb in weight, etc.).
Paying for an exit row is almost certainly cheaper than upgrading to premium classes, and many people take this view. If someone taller wants it because they can't take their regular seat, it'd be a case of "too bad, so sad...next time book faster and/or pony up the extra cash", and as I said, that's not socially unacceptable / frowned upon at the moment. There are plenty of people who will "carefully" select an exit row for extra comfort (using their status, paying for it or being ultra-quick) so they can enjoy their flight. It wouldn't matter if you approached them and you were tall, short, fat, thin, long legged, short legged, old, young, religion, race.... most of them most of the time wouldn't be giving up that seat easily at all, even with some "compensation".
I know at least one member of AFF who pays for premium class all the time because they are tall (Y pitch has scared them off). But not everyone can afford to pay for premium class all the time.
It's odd that aircraft designers have never considered that people would become much taller. Some of the Asian carriers (with 32" - 34" pitch) had a headstart for a long time, but a lot of carriers around the world still set at a "standard" 30" - 31" in most rows.
At a mere 1.75m tall, I'm not a tall person (not a very short person by any means), so I feel fairly comfortable no matter where I sit (although that's no excuse for not shaking the legs once in a while). Gee, we could start a new topic on all this discussion...