I've stood many times for the duration of train or bus rides much longer than a short flight, and which have gotten quite bumpy at times. I suspect most other FTers have as well, even if they'd rather not. (I'd rather sit, too.) If the airline folks can figure out the safety angle, I'd do it if that was the only way I could get from point A to point B or if the price difference was huge. I think most of the objections, other than "I'd rather be more comfortable" which applies equally to other forms of transportation, are just because we're not used to the concept.