no, placing blame on presidents does not help at all.
not only does it not help anything, its impossible to say that you could have predicted what was going to happen.
sure, after its all said and done, evidence trails might lead in specific directions, and learning from that knowledge is nothing but beneficial. to find out why things happened the way they did.
it doesn't have to automatically be labeled "a failure," nor does bill clinton or george bush have to bear the blame on their shoulders alone. they both clearly made mistakes, or at least did things that, retrospectively, they should have done differently. to pretend one of them didn't is idiotic.
but the point remains, its odd that you sometimes have to remember and remind others that the bad guys were the terrorists.
