Here's a thought to ponder. It appears obvious that the older generation would find it harder to tolerate long term long haul flying, so what about looking at it from a different perspective of this type of flying being for younger guys in the 20-40 year old range?
Please don't see this as antagonising any of you QFers (like you thought I was before), but maybe the whole "seniority" thing is partly where the problem lies. The Captain's (perhaps some older FO's as well) doing this flying are mostly in the latter stages on their careers/lives, and they're in these positions mostly because of seniority.
Perhaps it's not the type of flying people in the 45-65 year old age group should be doing?
Thoughts?