I think we should have kept our troops in Afghanistan. We shouldn't be withdrawing from any unstable region where we are already located. We also shouldn't be going into any new unstable regions.
When was the last time Afghanistan was stable pre-Taliban? Actually curious.
Likely many countries that have been used a token in the game of "Risk" played by the world's super powers, you could argue Afghanistan hasn't been stable in a long, long time (arguably going back to the 1940s/1950s). Depending on your definition of what counts as stable, you could argue there was a period of stability of about 5 years in the mid/late 70s, but that was after the Soviets had installed a puppet government as part of a coup. Then, the USSR and Afghanistan fought a 10-year war from the late 70s to the late 80s. Lots of instability in the 90s (though no massive war) and then 9/11 happened.
What's happening now is unfortunate, but the reality is that when the super powers use these countries to fight their proxy wars, the smaller countries almost always lose out in the end. You can make the case the US had a right to go in after 9/11 and that's fine. But, the US is responsible for fueling the rise of what became the Taliban when they partially funded the Afghans in the war against the USSR (for no real reason other than giving the bird to the Soviets).
Watch Charlie Wilson's War if you want the dumbed down cliffs notes.
On a purely fundamental level, if you're an Afghan under the age of 45, you've mostly lived your entire life with your country semi-occupied by a foreign power. If you take that into consideration, it's hard to get too peeved when many of them have the view that they just want the foreigners to get the eff out and leave them alone.