I enjoy my active duty job, being a pilot, I don't enjoy all the additional duties that become a much bigger time sink than your core job. The other problem with active duty, as has been stated, is that it's far from guaranteed that someone who likes to fly will be able to stay in for 20 years. 5-10 years ago you might have been able to stay away from staff assignments, make major, not make Lt Col and stay till 20, but those days are long gone. If you want to stay for 20 you have to make Lt Col, which means fighting for stats on your OPR by taking on more additional duties like organizing the Holiday Party and all the other un-official requirements to make it there. Unfortunately most don't figure out that the 20 is not guaranteed until they've got 12+ years in, and they missed the first chance to get out and into the guard.

The guard and reserves are a little nicer than active duty because your unit knows you better than AFPC knows it's active duty members. You also get to choose (usually) your deployments and also where you want to live. Every organization has it's problems and the grass isn't always greener, just like that famous motivational poster of a super hot chick, with the caption: "Somewhere, some dude is tired of putting up with her $hit"