and often fraudulent.  And most people, when they find that is lying to them in order to defraud them, react badly to it.  Thus the disdain we feel for bad art.

For the military, there's a built-in reason for manipulation and fraud.  Military recruits sign away many of their rights -- including the right to preserve their lives.  Throughout history soldiers have stood in lines and gotten themselves slaughtered for little or no personal gain.  Sentimentality is extremely useful in that it convinces soldiers that they want to become cannon fodder.