Thanks for all the interesting comments. I put this question to a friend in the travel trade and her observation was this:
“The time spent actually in the air is now quite a small proportion of the time sent on air travel. This is especially true of travel in Europe: for any flight less than about 2 hours, the time spent getting to and through the airport, waiting for luggage and getting to your final destination from the airport far exceeds the time in the air. And since the “non-air” part of the journey is (a) the same for everyone and (b) increasingly such a stressful and unenjoyable experience, it makes little difference to the *overall* experience however marginally more pleasant the limited time in the air is.
Of course the longer the journey, the more the air-time part matters and the more therefore there is advantage in a pleasant on-board experience. But our experience is that for short hops, people just want to get the travel part done: their expectations of enjoying it are pretty minimal anyway.”
Which makes sense to me, even if it is rather depressing.