1. There are no documents.
2. They contain still-sensitive information.
3. The people managing them are idiots.
Whatever's going on, it's certain that Saddam had connections to terrorists. Those have been reported --- and ignored --- many times over the past several years. It would be nice, very nice, to get some hard evidence on his connection to AQ. Which I personally believe he had.
Even when we do find hard evidence, the left will stick to 'but you can't PROVE they did 9-11' for a while longer.
Its a weak point, and even that might be blown out of the water if the connections are strong enough, but I'm sure thats what they WILL do.