Because, as I'm sure has been explained to you several dozen times by now, revealing the evidence would entail making public the communications between bin Laden and his people which we have intercepted.
And that very act would tell bin Laden, *and* every other enemy we have in the world, *exactly* what kinds of communications we can intercept (and by omission, which ones we can't).
Similarly, if any of the evidence came from our spies within the al Qaeda network, the pieces of information released would make it pretty obvious to bin Laden precisely who the rat(s) must be, which would endanger their lives.
How many more times does that need to be explained to you before it sinks in?
#12 is exactly right. Additionally, from what I understand, most of the black boxes were obliterated, only the Pennsylvania voice recorder was found, and they did release information that there were screams and the sounds of people fighting in the cockpit.
No, on September 10 I probably couldn't have found Afghanistan on a map. But now I sure can. And like most Americans, I've learned quite a bit in the past month and a half. And because of that, all I have to say now is:
Let's Roll!
As for proof, the proof was shown to leaders around the world who all agreed it was convincing and extensive. Are they part of the Great Conspiracy too?
Pissant's will remain pissant's no matter the evidence, that's the way of the world.
The boxes from the World Trade Center have not been recovered.