The fact we should not fight gorilla/insurgent type warfare applies. It's not what our military is designed to do.
There are problems being there; there would be different problems if we weren't there.
What's the solution? I don't know. A U.S. presence somewhere on the spectrum between policing Afghanistan (where we've been the last 13 years) and abandoning Afghanistan (where we where before 9/11).
Agreed. So why the hell are we still there with the luxury of 30 years of hindsight?