hi doma,
i believe in the possibility of ones that go horribly wrong. this may be one of them, in which some nasty, manipulative people sought to inflame tension in the arab world and thereby to procure goals they cannot otherwise reach. an attack on iran, for instance.
the trouble with these things is that the future creates unpredictable variables. so the tendency is for things to come unstrung.
as they did for bin laden. instead of establishing support for al qaeda and creating a new caliphate, in the end the 9/11 conspiracy made his organisation marginal. a weak brand. nothing more.
i don't buy the theory that someone other than obl's organisation was responsible.