I am not a fan of GW Bush, but I had no problems with him sending forces to Afghanistan when it was clear that 9/11 had been planned and coordinated there and that the Taliban was harboring Osama bin Laden.
I think almost ANY president, liberal or conservative, would have done the same.
Everyone knows how awkward it is to conduct a military campaign there, when the country has very little central government and a strong tradition of disliking most outsiders.....add to this the terrain, and the politics of working with Pakistan...etc... and I can't imagine an easy answer to HOW much and for HOW long to pursue this.

Somehow, the old expression "having a tiger by the tail, and afraid to let go" comes to mind.

The Taliban and Al Quaida have found it 'harder' to organize & conduct operations when they have to hide, but if we simply left, I suspect they would again reassert influence there because it IS in many ways the most convenient place to work from.