The problem is that it's not any other field. It's people with guns, by design more powerful than anything else anybody else has.

And, as Mao said, "all political power comes from a barrel of a gun". Which is why civilian control of the military is so important to preserve, and why the signs that the tail is wagging the dog (worship of all things military in US) is so disturbing.

With regards to family legacy of service, it was common for officers, but not quite so much for the enlisted ranks.