Decision-making in the armed forces is always performed by a "warrior class". The people who operate heavy war machinery are also career soldiers; conscripts are light infantry.
And there is a very real economic cost to mandatory military service. It only makes sense in the context of a small country (in terms of population) bordering a large aggressive neighbor, such as Finland or (possibly) Canada.
Armed forces culture is also incredibly important. Goal/mission oriented organizations are harder to co-opt than top-down command structure organizations.