Better physical fitness isn't the only reason for age waivers. Another reason for the age limit is based on physiological merit...degraded reaction times, rapidly approaching macular degeneration, and for those with prior service, years toward retirement. Since someone coming in at 28-30 vice 22-24 will be older at major milestones in their career, dept hd, etc...their reaction times will be slower than their counterparts, and by age 40 everyone has some form of macular degeneration (of the eye)...now, it may not be anything serious, but it does occur. The age limit is especially impt in the case of the Marine Corps, where it is a MINIMUM of 9 months from the time you enter OCS until you start flight training...so tack on another year to your waiver age...and that doesn't even count how long you have to wait for an OCS slot.
Before everyone jumps all over me about how in shape they are and how bogus the rules are let me just tell you I'm in the same boat (no pun intended) as the rest of you...I'm 30 with 8 years prior service. I think that personal character and previous military performance outweigh these physiological reasons for the age limit (to a point, obviously they aren't going to send someone 40 through flight school). However, for me at least, knowing some of the background made the policies easier to understand and "deal with"....althought I am still trying to push through and get an NFO slot.
Keep on pushing to make your dreams happen.