There is no reason to stay there after 2014. There was not a reason to stay after Osama was killed. We just do not know when to come home. We still have troops in Germany and Japan from WW2.
Germany and Japan were different situations. We were actually in war with countries which had well-defined leadership, and we had to rebuild the countries from the ground up. We may have overstayed our welcome, but they aren't bombing our bases to make us leave, either. And, they don't routinely engage in human rights abuses, like stoning. Their females get an education and can drive cars.
We need to get the hell out of Afghanistan. There is no country to rebuild because we didn't destroy anything.