I think the headline says it all:
Air Force’s pitch to retirees: Come back! No bonus or promotion, though
Retired officer, enlisted can rejoin active duty amid shortfalls
^ that's just one news source and it was from a couple of months back so I don't know what's current.
So you still have to pass height/weight and the PT tests and do all of the other reindeer games, you no longer get your retirement pension, you're subject to PCS, you keep your same pay grade and no bonuses? I'm making FAR more money now than I did when I was on active duty, largely due to my pension and disability. There is very little incentive for someone like me (and I expect that I'm the norm) to take them up on the offer, especially since the same conditions that prompted many of us to leave when we did are either still in place, or weren't remedied to our satisfaction.