Ah well, the old saying of hindsight certainly applies here as well. Hopefully we can get the right people in place to adapt, overcome, and win this conflict.
The French kept the Japanese Army to keep order in SE Asia after WW II.
Did we keep the German Army after WW II intact, or did we disband it, develop de-Nazification procedures and start again ?
Would you keep the Baathist army without finding out where each and every member's loyalties lay ? And, would you confine them under guard in barracks or let them go home and apply again for the new Army ?
Seems like you are a little short on the logistics and consequences of what you advocate.
What I do like about our Army is that they learn and adapt quickly. Cynically speaking, no peace time exercise can substitute for the real war experience. This "benefit" surely does not come cheap (in blood and money) but may become priceless later.
What Iraqi Army? They melted away and were not heard from again (Other than the ones who joined the insurgency) until we stopped paying them for not showing up!