I love Rumsfeld, and the prosecution of this war has been maasterful. But I agree with your take. We need to be building a leaner more agile force, but this should not mean eliminating our strategic depth, so to speak.
We were able to smash Iraq, with minimal loss of life on our side, because we train and prepare to fight a much stronger enemy. If we were designing our force for an economical execution of a confrontation with a mid-sized force such as Iraq's, we could do this with a much smaller force, but with perhaps much less margin for error.
If we determine to separate Colombia from the clutches of the FARC, or topple Chavez, we aren't going to need a million infantrymen. We will need a few thousand Special Forces, and some good intel, and perhaps some well directed bribery. The Iraq model works.
But if our next war involves separating Uzbekistan from the Chinese Army, and two or three other simultaneous conflagrations, we might wish we had a little more depth to draw on.
But one thing the Iraq model must teach us; you must control the sky. If your enemy gets control of the air, the infantryman without air cover is a soon-to-be-dead-man.