Okay. Why do we have them, then? Why do we have an 'Africa Command', when we can't even command a street corner in South Chicago?
I recall a possibly-apocryphal conversation beween a French and British leader, after the latter county had signed a mutual-assistance treaty with the former. "In the event of a war, how many men do you want us to send you?", the British leader asked. The Frenchman replied, "Just one. And we shall see to it that he is killed."
Are they a tripwire, to draw us into the coming conflict between Bongo-Bongoland and Absurdistan?
We can't dominate the world the way we did when we just faced the Soviets. We're moving to a multi-polar world, and it will be full of conflicts and outright wars. We need to stay out of them unless our direct national interests are involved, especially with the way our military is going.
No one is going to invade us. And if we remain armed to the teeth with nuclear weapons and ready to unleash Armageddon on anyone who launches a nuclear attack against, we probably won't face one. (Our enemies probably know they just have to wait until we collapse from within.)