We should have defined our enemy as Afghanistan or the Taliban or Al Qaeda or Islam. We should have fought that group and killed as many people as it took to get them to surrender. If others next to them were killed because of miscommunication of our enemy's whereabouts, oh well. It happens in war. If they don't like it they shouldn't attack us -- especially killing thousands of our civilians.
Our enemy was and still is Islamist Extremists. Bin Laden was the leader of the worst Islamic terrorist organization in the world. Killing him was akin to killing Hitler. IF you took out the rest of the Al Qaeda command structure with him, it would have sent a message to not attack the US for the next 50 years.
It would have also given all the other enemies the clear message that we were not afraid to use every weapon in our arsenal including nuclear weapons to defeat an enemy.