That's an interesting observation, but I don't really think that observing posts on an airline pilot message board is really a fair barometer of the contentment of military pilots about the airline industry. Obviously anyone who is reading this board has some sort of interest in getting into the airlines, so they're generally going to have a positive attitude about it. You're not going to get the military equivelent of "SkyHigh" on here talking about how terrible it all is, because that dude is probably off doing something other than hawking the fight on an airline pilot board.
Personally, I think that you don't see military guys b*tching about things happening in the airline biz because it's so different than the lifestyle of a military pilot. When an ex-military pilot goes to an airline, he gets to basically solve all the things that military pilots hate most about their jobs -- there are no "additional duties", no desk-work BS related to trying to get promoted or fill the latest career-square, and the pay is generally much better. Oh, yeah, and you're not getting shot at, living in tents on a 4-month deployment to the desert where you can't drink or have sex.
It's not all roses, however, and you lose many of the things that are great about flying in the military -- the exciting flying, the sense of mission, the tight squadron camraderie. It's a tradeoff, but I think that by the time a military guy gets to an airline seat there is not too much to b*tch about.
24G's reply has some merit, though. Not to imply that civilian-trained and employed pilots don't, but military guys have to eat many sh*t sandwiches often enough that they're used to it.