contrary to popular belief, being a DXO is not all suns and roses. it demands a certain level of competency and committment.
mindef is not a place where you can just screw up and say oh wells.. you immediate boss might not even have the power to cover for you.
as such, there is certain amount of expectations and stress that comes with it (true for all jobs haha).
mindef demands new ideas and projects every year on top of the routine work. and this policy is not for everyone. people like me only wants to do my primary job well. but because of the many many extra projects and stuffs, we do feel disillusioned. we dont get paid extra. we tend to spend more time doing secondary stuffs instead of our primary job because this is how the system works. in the end, managements looks into your extra during ranking, often neglecting that you did your primary role well.
therefore, many leave because of the above.
mindef is basically cutting manpower and throwing a 3 man job into 1 man. over time, anyone will feel tired, abused and overused.
from my time here, i saw many people leave, of all ranks. the experience is lost. knowledge is not retained, making it harder for new DXOs to perform. red-tapes also exist and the system is filled with people who only wants to save money to look good(mostly senior management), without thinking about the implications downstream.
as for the job openings, most openings are probably new estabs, meaning newly created positions. not too sure on this as i cant speak for all DXO positions.