I don’t see it so much as an MI fail, but as a total and complete cultural fail or the US in particular and “The West” in general.
Obama, at Mogadishu, called it correct in his fatwhaa. We are “paper tigers”.
We, as a people, are not currently capable of fighting to win in any endeavor, military or otherwise.
The intel fail is just a symptom of our rot caused disease.
As the English writer G.K. Chesterton said, "The only defensible war is a war of defense... A real soldier does not fight because he has something that he hates in front of him. He fights because he has something that he loves behind his back."
I could add a lot of superfluous follow-up commentary on this. But it would be just that, so I won't.
As I said in my earlier comment, the Obama administration is responsible for this.
And it was intentional.