A big part of it is getting told how valuable you are, how necessary to the force, how you are vital to national defense...then getting passed over. The passing over shows you what the Air Force values, and it's not whatever you've been doing for the last 15+ years. So if you've even a little on the fence, it's an added incentive to join an organization that DOES value what you do, and shows it through your pay and seniority numbers (the airlines) instead of staying in an organization that claims to value you but acts as if it does not.
The extra pay is nice, though. For me, due to my ADSC for the bonus, it'll translate into an extra ~$800/month in retirement, or just shy of ~$10K a year, vs retiring as a major.