I think the main problem is that there is, unfortunately, a notable qualitative difference between a "volunteer" army and a conscripted one. This is not in any way to detract from those who have served our country after being pressed into service, but the fact is that drafted soldiers have tended to be more likely to be injured or to develop chronic psychological problems than "professional" soldiers. Historically, you use only implement a draft when you are expecting heavy casualties. Modern military tactics focus on minimizing casualties (not that previous generations didn't care about that, but it is much more a focus in our technicolor world of 24-hour news coverage). Bottom line, though, is that commanders would rather not field conscripts.
It is my understanding that the military is moving to a model that allows for quicker, lighter, more laser-focused tactical strikes to diminish opposing forces without having to commit heavy troops. The personnel-heavy end, then, becomes occupation/peacekeeping. I guess, theoretically, we could draft peacekeepers after a wide-scale conflict, but I kind of doubt it.