"Is it really that much of a stretch to believe that Bush and Cheney were/are incompetent and overconfident boobs who were caught with their pants down on 9/11? Really?"
You bet it is. Getting everyone to think that they were incompetent was one of the master strokes of the operation. Dick Cheney incompetent? Only when he wants YOU to think he is.

The prior warnings were all cooked up false back story. They served a few purposes. Because of their existence studio talking heads could say with authority that Osama did it even as early as when the towers were still standing. You always have to tell the punters what the product is that is right in front of their eyes as soon as possible. Don't leave them time to have thoughts of their own.

Secondly it let the top brass off being considered as involved. No they just stupidly didn't act on the warnings. But the biggest benefit was that these so called warnings were used as providing proof of Osamas involvement BEFOREthe event, removing any necessity for a proper police investigation AFTER the event.

So they could jump in calling it an act of war which is what they were going to do all along whilst scuttling any need in the public's mind for a through criminal investigation that they sure as hell didn't want.

Got to hand it to them. Those "incompetents" sure were slick.