I was gonna make an edit and say exactly what you said. Well put. If the moral support is needed that badly then the situation is already pretty grim.Depends on the situation and time period. In general (no pun intended), it's a patently stupid idea especially after the introduction of gunpowder onward (see the Napoleonic Wars if you want to see examples of French officers getting routinely killed in the front); however there are situations where it's a necessary evil when 1) there is practically no reserves left and/or the only reserves left are with the general and as such must commit to them as Julian mentioned (see for example Caesar in the Siege of Alesia) or 2) the general feels that it's necessary to risk his person in a particular point in the battlefield just to preserve the whole position.
@_01 that's a summary of Carl Benjamin in general. Anything he tries to regurgitate or give his take on sounds dumber than he thinks in his head it would sound.