Skill
There is quite a difference between a fighter aircraft and an airliner. If you're a good fighter pilot, doesn't mean you are a good line pilot. This should be understood by airline management, when deciding on hiring and training new pilots.
In some cultures you are a hero when you have a military background. We don't need "heroes" on the flightdeck. We need professionals struggling every day to improve themselves a bit more. (Ex military pilots included!)