I picked up on that one right away. A Freeper who claimed to be an electrical engineer posted a message on an earlier thread indicating that these bombs were not only very simple, but also exposed the two mutants to some potential danger because of the possibility of an accidental detonation when using a remote-control car detonation device like what has been described for these bombs.
From the FBI's standpoint, I think it sounds a lot better to say that they were unable to prevent these attacks because they were staged by professionals than to tell the truth, which is that they couldn't track these guys through the usual sigint and informant networks because they were just a couple of Islamist palookas screwing around.
It's the Katrina syndrome - the public blames Bush for Katrina's aftermath even though he did everything in his power. Some things are just out of your hands. I don't doubt the FBI did all it reasonably could. I suspect there are huge numbers of domestic Muslims (and non-Muslims who want to see what the enemy looks like) who view jihadist web sites. If you added every one of them up, you'd end up with tens of thousands of suspects, if not more. There's nowhere near enough manpower to cover all of them.