Would it really be so bad if we left those 6th century barbarians to sit in their own filth and stupidity?
Yes. Unfortunately. The real problem, as all of this shows, is Pakistan - a nuclear armed rogue state, which has been exporting nuclear weapons technology, and without which the Taliban and Al Queda could not survive and without which Bin Laden would have been dead meat almost 10 years ago. And Pakistan's neighbor, Iran.
Ultimately, we are going to have to put paid to both. Perhaps the Indians can deal with the Pakistanis - rough justice for all the Muslim oppression of India before 1947 (even under the Brits, many muzzie local rulers were still in place) and the Indians have nukes, too. Pakistan could not win a war with India. Iran is a tougher nut. Do they have the bomb yet? Dunno, but they do need to be dealt with.