Again, I concede that Bagram is located in the middle of nowhere. That's the exact reason that it would be really difficult to get to for our citizens and the Afghani's that we apparently would like to save if things went south. Establishing a perimeter doesn't actually do anything for an IED. There are still people (Civilians) around the perimeter. There are likely more people required to man a bigger perimeter (Soldiers), and a bomb in the right spot will still kill a crap load of people including our own. A perimeter doesn't really do anything (besides possibly keep people from rushing the planes like they did but I feel like we are willing to let that level of people go considering the number that we saved).
I would challenge you to go look at the soviet withdrawal in the late 80's and the things they dealt with. Do you think they did a materially better job? Or do you think all of their commanders were just inept too? After all, a ton of soviet equipment fell into the hands of Afghanistan which they're still using today.
BTW here's an interesting transcript of a communication between one of the Soviet commanders and the US CIA station chief in Islamabad as the Soviets withdrew from Afghanistan. Can you not imagine the Russians doing the same sort of thing just to spite us?
Botshan-Kharchenko: You must understand, Mr. Buurdon, that these attacks against our troops as they withdraw must stop.
Bearden: And if they don't?
Botshan-Kharchenko: Then perhaps we will halt our withdrawal. Then what will you do?
Bearden: It is not what I will do, Counselor; it is what the Afghans will do. And I think they will simply keep on fighting and killing your soldiers until you finally just go home.
Botshan-Kharchenko: But you have some control over such matters.
Bearden: No one has control over such matters, Counselor, except the Soviet Union.
Botshan-Kharchenko: Mr. Buurdon, you must still understand that there will be consequences if these attacks continue.
Bearden: I am sure there will be, Counselor.[4]:153 [8]:354