From A Jacksonian's Three Organizations, One Quagmire:
By not having a conscript military, the US invests its time and energy on those volunteering to take up military work as a profession. That is not understood as a profession by the other professional classes in America, and those classes tend to devolve military work as 'shooting and killing' only. That does happen, yes, and military conflict requires that the wilingness to counter an enemy with brutal means must be done for survival of one's own forces and to reach the goals of the Nation in such a conflict. Denigration of all other professional classes, but particularly in academia, has lowered the ability of the US population to understand military work and how it works. Without knowing the why it is done the way it is, and how things are achieved not just by killing, nearly an entire generation of Americans are left with very little concept of the utility and necessity of military power.