Boo, here is an example of the fallacy of your thinking.
Bush knew that because of the timeline of events -- i.e. he knew it couldn't be completed on his watch -- that he could not and did not want to completely commit the next president, whoever that was going to be, to 100% of the 2008 SOFA. So he negotiated a tentative or placeholder SOFA to accommodate certain political goals (for him AND Maliki) addressing immunity for current troops and contractors, for example, and then left lots of wiggle room for the next president to do what they needed to do depending on conditions on the ground to negotiate the final SOFA.
In other words, why would a president who knows the next president had to take up the mantel, hem that president in when in fact they are giving that president room to maneuver. This is how all most all presidents have handled foreign policy...and shocked you don't know how it's done.
We have come full circle now. Obama did just that, he maneuvered right out of the SOFA Bush timeline creating this mess all himself.
The time line set in the SOFA signed by President Bush was followed. Troops were out of the cities in mid 2009 and out of the country by 2012.
Article 24
Withdrawal of the United States Forces from Iraq
Recognizing the performance and increasing capacity of the Iraqi Security Forces, the assumption of full security responsibility by those Forces, and based upon the strong relationship between the Parties, an agreement on the following has been reached:
1. All the United States Forces shall withdraw from all Iraqi territory no later than December 31, 2011.
2. All United States combat forces shall withdraw from Iraqi cities, villages, and localities no later than the time at which Iraqi Security Forces assume full responsibility for security in an Iraqi province, provided that such withdrawal is completed no later than June 30, 2009.
3. United States combat forces withdrawn pursuant to paragraph 2 above shall be stationed in the agreed facilities and areas outside cities, villages, and localities to be designated by the JMOCC before the date established in paragraph 2 above.
4. The United States recognizes the sovereign right of the Government of Iraq to request the departure of the United States Forces from Iraq at any time. The Government of Iraq recognizes the sovereign right of the United States to withdraw the United States Forces from Iraq at any time.
5. The Parties agree to establish mechanisms and arrangements to reduce the number of the United States Forces during the periods of time that have been determined, and they shall agree on the locations where the United States Forces will be present.