By the end of the Civil War, the Union had purged its high command of non-Academy generals. There were exceptions, like Logan and Blair functioning in field commands as major generals, but those wholly self-taught were crowded out of the center.
There is no study of this event, nor do we have a handy source for contemporary back and forth on the issue. Here's a try at listing the positions of the two camps.
(1) Academy training does not prepare officers for war.
(2) The professionals will always consist of a stale, parochial talent pool organized by date of rank, not merit.
(3) Professionals will fall prey to their own class interests, putting these above the country's need.
(4) Professional officers lack the vision, energy and life experience of successful Americans civil leaders.
(5) Talented men can learn on-the-job and by reading.
(6) Professionals become preoccupied with military punctillio and minutia to the detriment of the mission.
(7) Professionals cannot connect with a citizen army mobilized by intense political or patriotic sentiment (cannot bring out their best).
(1) Civilians in high positions reduce efficiency.
(2) Civilians pursue individual and political (non-military) agendas.
(3) Civilian appointees make technical errors that cost lives.
(4) Civilians often have divided interests (businesses left behind, political careers, etc.) and lose focus.
(5) Civilian appointees will discriminate against professionals within their commands.
(6) Civilians curry favor with the rank and file.
(7) Appointees will apply non-military considerations in making military decisions.
This little list will be our jumping off point for looking at some ideas in the modern military reform movement. More tomorrow.