LJ: I'm sorry to hear of your losses.
Back to the original question: I've wondered the same thing. I started practising medicine in 2009 and have looked after a number of WWII pilots, as well as a number of aircraft mechanics. I have also looked after a few people who served in various roles in the army, but it seems to me that the RAF personnel seemed to be disproportionately represented and to be in particularly good nick for their ages.
Impressions can mislead, but it would be worth looking into.