If it was a Peace Prize, its timing could not have been more unfortunate. And the burden of this clearly showed on Obama and hence his defensive "what else can I do" acceptance speech.
Here's what I think he could have done. Decline to accept the Nobel.
An Obama who then explained that yes, he was the Commander-in-Chief of a nation waging two wars, and there was that part of his responsibility as ??the President of the US of A that he is bound to execute, even as he stays hopeful and works towards a solution for peace, would have kept alive the vision he attempted to define through his oratory. He would have done much better to decline, 'for now', the Nobel and offered to pick it up when his dream and vision actually translate to reality. That would've really turned things around for him everywhere.
Oh well, I guess the big medal was a bit too much to resist. He's human, too, after all.