Sanka freeze dried version (collapsing some of the points because they look redundant or at least closely related) with comments:
1 & 4. Bush and company were stubbornly resistant to facts on the ground. They did not plan for the difficulties inherent in state building, and held naive views as to its ease. Did not want to admit they were wrong.
2 & 8. Reading conditions in light of the overall goal of nation building is tricky business, as the factors are numerous and individually multifaceted, and give ambiguous support to positive and negative readings of progress toward the goal.
3. Given that state building is a long-term project (even if naively entered into) the more lives, and cost devoted to it, the more there is a desire to see it through. One does not want to spend blood and treasure pointlessly.
5. A different leadership team must be in place to carry out the extraction. It takes time to build a new team. Therefore, extraction will only occur after a protracted process of change in leadership. (Is this a universal claim? Not sure it's necessarily true, though it might be contingently true.)
6. States will often try different ways of meeting strategic goals. Implementation of these takes time. There is also a natural inclination to give them time to work. (He obviously has COIN in mind here. Once decided upon, in 06, it had to be given sufficient time to be implemented before its efficacy could be judged.)
7. Like Jim Kirk the military "doesn't believe in the no-win scenario".
9. States like to establish and keep credibility. So rather than toss in the towel, they tough it out, and exaggerate the dangers of damaged street cred. Here is Walt:
This was a common refrain during the Vietnam War, of course, and we hear loud echoes of it now. If we get out of Afghanistan, we are told, al Qaeda will be emboldened, its recruitment will soar, and our allies around the world will conclude we are wimps and abandon us. Of course, getting out of Vietnam didn't have any of these effects (the United States won the Cold War, remember?) and it is just as likely that getting out of Afghanistan would undercut jihadi narratives about Western imperialism and allow the United States to focus its military efforts on places that really matter. Indeed, U.S. credibility may suffer far more if it keeps squandering its power on costly but unnecessary conflicts.
Some observations: Yes, we won the cold war, but in Vietnam and Cambodia, the locals paid the price for our retreat. What is more, that retreat did lead to a perception of the United States as not having the stomach for long conflicts, something that bin Laden, now that you mention him, banks on as a goad to recruitment, and as a rallying cry to the true believers. It is something he continually harps in his writings and pronouncements (assuming of course he's still alive..cough cough..Iran..cough cough).
As regards undercutting "the narrative" it would seem that HOW we get out has important effects on any potential undercutting. Suppose we just got out of Afghanistan leaving some autocrat and without making any serious efforts to protect the cooperating citizenry from reprisals. The Taliban would no doubt move in, do their barbarian thing, and upon victory over the local government, would proclaim victory, would they not? And, it would sure look like a correct assessment. Would that not also feed the opinion in the Middle East that U.S. strategy is really just Realism Lite, and while it talks a good game about freedom for all, that talk is not serious, and is undertaken either half-heartedly or cynically, in the interests of Realpolitik. Seems likely that perception would indeed be fed. That's a win for the enemy.
On the other hand, suppose we do as we have done in Iraq, taking great pains to create an autonomous and ostensibly democratic government of and by the people that is, by any objective standard, a vast improvement over the autocratic norm for the region (yes including autocracies we have sometimes "realistically" supported in the past), and THEN we leave. Will this feed the narrative? It doesn't seem so. In fact, it works counter to 'the narrative.'
When the time is right, we can leave. We in effect say, by using the COIN strategy, seeing it through to the stage of a nascent and stable nation (in the true sense of that word):
"We've spent blood and treasure so that you have an opportunity for a new beginning, something like civic freedom, and a better life. Don't screw it up, and we won't leave you in the lurch" That's the message we send now. An improvement on old school realism, and a direct threat to 'the narrative'.
10. Nations in general have Captain Kirk's attitude. They don't like to lose.
Final note: There is a lack in the list of reasons. None of them mention a moral obligation we have, once we have entered into the project of deposing autocrats and nation building, to finish the work. That obligation holds if we have good reason to believe that a vulnerable populace will be placed at the whims of barbarians upon our exit. We had good reason to believe that in Vietnam, and the political decision was made to leave anyway. The killing fields resulted. The narrative was fed. That obligation also holds regardless of your opinion as to the advisability of having in the first instance, entered into war in Iraq or Afghanistan, and it also holds regardless of your opinion as to the good will or veracity of arguments made in favor of the wars. The realist would rather not think about that.