But, Petraeus is very very late in the game, however, and we have been through a lot of civilian leaders who had no military experience at all, and a lot of military officers who were just paper pushing bureaucrats rather than strategists. It took a long long time for ideological purity to give way to military necessity in Iraq - 5 years too long.
I don't know why folks are arguing against the point. It is an historic malady of peacetime armies - everywhere - at all times. Lincoln had to run through a lot of McClellands before he got to Grant - but he knew it and he found Grant. The Navy had to run through a lot of submarine commanders in WWII before it got commanders who would shoot torpedoes at Jap ships, and then the Navy had to run through a lot more shore commanders before they got some who were willing to fix design flaws in torpedos so that they would actually blow up Japanese ships when they hit. And a lot of men lost their lives and a lot of missions were wasted fixing peacetime leadership problems. But Roosevelt had an eye for good officers and the top military leadership was pretty good going into the war. I don't think Bush or his advisors have such an eye for military talent.
We are 6 years into this. WWII would have been long over by this point. In Vietnam we simply never fixed the leadership or strategic problems. Good strategic planning probably would have kept us from getting into the war. Kennedy stayed out of Vietnam on the advice of MacArthur. MacArthur's advice turned out to be sound.
One of the possible outcomes of careful strategic thinking is that the cost of the operation far exceeds any likely achievable benefit. Even if Iraq starts to wind down shortly and we manage to reduce out operating costs to reasonable levels within the next 2-3 years, which is everyone's fondest hope maybe involving a bit of wishful thinking, it is going to be many many years of hard work to put the US back together again, take apart a staggeringly expensive so-called security apparatus (checking every blond 6 year old who boards a plane and every bank transaction looking for terrorists), pay off the debt, address our energy security problems in a manner that makes any difference. Will it be worth it for a free and democratic Iraq that may not end up being so free and so democratic? History will have to be judge, but at best it is going to be an awfully close call.
Are folks going to be grateful? The Saudis sure aren't grateful to us right now, and they ought to be.
We were warned, going in, that it would be a long war. But, perhaps, our society is so inured to immediate gratification that we're not prepared to fight such a long war anymore.
Strategically, Iraq, Afghanistan and al-Qaeda present a very difficult situation. There's just no successful history of such operations. For example, I'm aware of only two "wars of insurgency" that have been fought successfully --
a. The British in Malaya
b. The so-called Moro War in The Phillipines.
In addition, there was much to be learned from the French experience in The Algerian War, 1954-82
I believe Iraq and Afghanistan are on their way to providing a third example. Viet Nam would've, as well, had it not been for the politicians (who probably shouldn't have put us in the position to start with).
Your point about the peacetime military is well-taken. There is no evidence that the U.S. military (or any other, for that matter) has ever been prepared to fight "the next war". Invariably, the initial command fails...there is floundering...and then, finally, somebody figures out what to do.