FB: There's not much basis for an equitable comparison between WWII and what has happened in Iraq re: effectiveness of the US military and the casualty rate. (One could argue the latter is instead simply a reflection of the disorganized, ineffective and relatively limited resistance put up by the opponent against superior forces.)
Germany and Japan were well armed, had navies and air forces in addition to ground troops and put up far greater and sustained resistance in a global theater for almost 4 years (the term of US involvement). Not surprising the US casualty rate was higher. One could probably say that of the US Civil War also, even just picking one side for comparison. The Battle of Antietam just in one day resulted in over 26,000 casualties, about 14K Confederate to approx 12K Union.
In contrast to the opponents in WW II, a good portion of Iraq's air force (what was left of it from 1991) was found buried in the sand and reportedly the Iraqi air force never even left the ground much less engaged in combat. The Iraqi army, again much the worse for wear after 1991, put up relatively desultory resistance compared to the combatants of WWII. It distinguished itself primarily in retreat and abandonment. There was no naval warfare to speak of and no Iraqi wolf packs prowled the Persian Gulf. Of course Iraq put up more of a fight than Panama or Grenada (where I believe it was determined that the majority of all US casualties were the result of friendly fire), but comparisons to the conflict in WW II are simply not apt as a equivalent gauge of military effectiveness against a very different opponent in considerably different circumstances.
As now often noted, since the cessation of "major hostilities" in Iraq the casualties have exceeded those incurred during the time of "major hostilities." Does that statistic reflect the ineffectiveness of the US military against an armed and motivated insurgency? Not necessarily since the situation isn't quite that simple, although I suppose someone could make that case. One can use stats for all sorts of purposes and often they can obscure more than they reveal.
The recitation of such stats of course give cold comfort and are perhaps even offensive to those who lost loved ones or those wounded in such conflicts, whether combatants or not. And the effectiveness of the US actions in Iraq in bringing democracy and stability to the area and reducing the threat of further terrorist activities remain to be seen.