I'm not a big Bush fan by any means, but I think these attacks on him are stupid. Does anyone really think that he, personally, knew these attacks were coming and just ignored it? He relies on his advisors and the heads of these agencies to keep him informed.
I do think our various "intelligence" agencies need an ass-reaming, though. It seems clear that the FBI, CIA, and other intelligence and law-enforcement agencies were not communicating effectively. This has been a problem for a long time, on a variety of matters.
I do know that one change Dubya has made has been that the FBI and the CIA now give their briefings to him at THE SAME TIME, so they're actually in the same room sharing info. If they'd been doing this last summer, would anyone have connected the dots? Who knows - that's going to be one of those unanswerable questions that historians will debate forever. But someone might have.