I get the impression a permanent standing army is something that needs nobles or even the king for. Until then, all military are Militia. They're never meant to be professionals.
Well i wouldn't be against the fact Noble give something to your fort. Nobles are knows to be military leaders, religious, and also leader for great projects (like make a 10z level tower, rather than give me an artifact), they could also attract better quality workers (artist) from the map (even have some other race worker coming), like some great emperor did in real life. Thats just ideas, but it would be nice.
Mysterious i would really have done this, but the problem is that they seam to go civilian you want it or not, i think something is bugged about this, i also taught of making them educator for new recruits, since those i was talking about really had great skills, any kind of smooth "retirement" would have been great. I aslo wanted to let them alone when i send the squad to do some order like kill or station, but my game crash when i pick only few soldiers from a squad.
There is an other possibility to resolve the problem, if the vets are over trained and don't want to do any other type of job (as it was in 40), then disable the "go civilian" feature on them. Now i don't code the game, and i kind of didn't play for maybe a year, so if i say stupid things just don't mind about it.