At Obsidian Wings, Hilzoy notes that if Israel is faced with two choices:
A) Not respond to the occasional provocation by Hezbollah, such as a rocket or border ambush, or;
B) Respond with such a gross overreaction that you incite the Lebanese population in to Hezbollah's arms, and yet still fail to stop rocket attacks or Hezbollah ambushes,
the choice should be clear.
Similarly, if the United States is faced with the choice in Iraq of either:
A) Leaving now, and letting the civil war take it's course, or;
B) Staying, failing in any way to prevent the civil war, and succeeding only in getting additional Americans and Iraqis killed,
the choice should be equally clear.
Look: military forces aren't metaphors. They are real, steel-and-gunpowder things that kill people. Using military force "to send a message" about how big and tough you are is an incredibly bad idea, as both Iraq and Lebanon show. What happens when the other guy calls your bluff?
Well, you look even weaker than you did before you did a stupid thing, except this time your troops are in the middle of a war.
The one advantage to Clinton's policy of the "air force only" war was that it demonstrated America's ability to bomb the occasional Serbian hospital without opening America up to counterattack. Whatever we may think of that ethically or morally, it certainly allowed America to demonstrate its power without risking defeat.
Trying to respond to provocations - or, in the case of Iraq, zero provocation - with military force and failing to accomplish material aims is pretty much the worst of all possible worlds.