Problem I have, John, is when those principles and lessons are operationalized for current and future action. For example, when Army planners and thinkers consider the problem in Astan there seems to be a common consensus that more troops are needed on the ground and applied in a way that pushes them out into small combat outposts in order to secure the population, to separate the insurgents from the people, and from the building the nation can begin. Coin expert John Nagl has recently said as much on a recent Frontline show on Astan. But this is my whole point and criticism of what happens when principles turn to hard and fast rules, to a fetish, to dogma, and directs current and future actions on the ground.
As one who is much more knowledgeable on Afghanistan than Iraq, I share your fear. For example, there are places in Afghanistan where "protect the population" is not going to work (in my judgment), but, there are places it likely will work. FWIW, my view is that in Afghanistan there is no single principle or "truth" that will lead to success - the country is much more diverse than Iraq and much too diverse for any single strategy. My main worry is that we don't understand Afghanistan well enough to successfully discover and employ a winning strategy to begin with.

I also agree about the danger of hard-and-fast rules and the blind importation of strategies from one theater or period of history to somewhere else. On the other hand, I don't think one should preclude such templating either as long as a proper and cogent analysis of the situation justifies it.

I might therefore suggest the problem you identify is really a symptom of another problem - a failure to properly analyze and understand the operating environment compounded by a failure by the conventional forces, more generally, to prepare to operate in those environments. As Rob eloquently pointed out, Neil was placed in a position where he was forced to develop an ad hoc solution with little in the way of a PME and doctrinal foundation. Had that foundation existed, Neil's essay would likely be on something other than Krepenivich and the current debate of COIN would be quite different.

So I think the point others have tried to make is that Neil (and so many others) should never have been put in the position of making ad hoc decisions with a significant (and preventable) educational deficit. It therefore seems prudent to me to provide officers with a diverse PME background that covers the full spectrum of conflict so they are prepared to better understand their operating environment and, by extension, better able to develop sound strategies and tactics for that environment. An additional effect of this approach is that officers will more easily recognize when and where a particular COIN (in this case) approach will work and where it will not. So the entire problem you identify is due in large part to effects of not properly preparing for COIN to begin with.

If I understand your argument correctly, your fear is that ad hoc solutions implemented in Iraq are being elevated to the level of "truth" or sound principle without sound and rigorous analysis. I tend to agree (to a certain extent at least) and strongly believe that challenging these ideas is both necessary and beneficial. By continuing to challenge accepted wisdom you are continuing to perform a valuable service to the armed forces and nation in this regard.