Typically lame response on the part of AF commanders.

Part of the reason their aircraft inventory is so old is that they've insisted on developing high-end, high price dream machines that take years to reach any sort of operational status. This means they've been flying the wings off the A-10 (which they constantly want to retire), the B-52 (which will outlast both the B-1 and B-2 according to the AF's own operations estimates), and their entire lift fleet (which they hate maintaining since it takes away from the fighters and bombers).

The other reason this has hit the AF so hard is their own culture, which trades on dreams and machines at the expense of personnel. The machines feed off the dreams, which explains why their tanker buy is so late in the game. Tankers don't have the zip or glamor of fighters (or the big bombers), so you ignore them until there's no other option. It's depressing when you work around it every day.