"Why Does It Matter?"
First of all, Mrs. Clinton, we in the military have a policy that is implemented from the bottom to the top: we do not leave our wounded -- or even our dead -- behind. Yet not only did the Obama Administration leave people behind, they did so when they had plenty of available forces to rescue them. That sends a message to everyone that wears a uniform, or who has ever worn a uniform: this administration doesn't care about you. Not only did they leave Americans behind, not only did they withhold support that was readily available, but they actually relieved commanders of their position that pushed hard to actually do what they were trained to do, and what had been instilled into them from the moment they entered the military.
Can any reader imagine what this does to morale among the lower ranks? Among the officers that have sworn to uphold the Constitution, and to do all they can to rescue any wounded or dead comrades? Any officer who believes the Constitution is above the petty behavior of elected or appointed official? It's deadly. If it were MEANT to destroy faith among the military in their leaders, it couldn't be more deadly.
The decline in morale among the military is only slightly greater than that among parents and loved ones of those, not only in the military, but anyone who is serving in what could at any moment become a hostile environment. There is no faith that any member of this administration would go out of its way to rescue hostages, anywhere. If you work for an embassy, if you're part of the military assigned to an embassy, or if you're part of a military unit assigned to a hostile war zone, you're on your own if you're captured. If you're just an employee of a multi-national company and happen to work in what could be a hostile place (I.E., Algeria), you can't expect this administration to care. This administration won't put itself out on your behalf, or even on your nation's behalf, if it might cost them even one vote in the next election, or one bit of bad press.
We've come a long way in the last 100 years, from an armed force that was hardly capable of wiping the nose of a tinhorn guerilla (Pancho Villa) to the finest and best military in the world today. Yet it only takes one incident like Benghazi to destroy it all THAT'S what difference it makes, Madame Secretary of State. Both you and your boss are idiots for not understanding that.