Gah! Petrus wrote a great post. We should be discussing his arguments.
He has a good point , however .....The Taliban regime was the only period of peace in Afghanistan since the soviet invasion which means that the resources required to replace it effectively were huge and success not guaranteed.

It wasn't a period of peace , before they withdrew in the face of the coming invasion the war in the north was still ongoing, they had just fought against 3 large rebellions in the South and East(supposedly their secure heartland) and had narrowly avoided a massive Iranian invasion .

Afghanistan was the islamist equivalent to a Pakistani protectorate, so limitation of the response to this country was not enough to cut the roots.
Any thoughts on the clashes between the Aghan government army and the Pakistan army in Afghanistan last week , or the reports that the US delegation ambushed in Pakistan (and the US soldier killed in that ambush) were attacked by Pakistani soldiers ?