This is an interesting argument from John Mueller:
In his excellent book, The Far Enemy, Fawaz Gerges argues that mainstream Islamists–the vast majority within the Islamist political movement–have given up on the use of force except perhaps against Israel, and that the remaining jihadis who are still willing to apply violence constituted a tiny minority before 9/11. But he goes on to note that the vast majority even of this small group primarily focuses on various "infidel" Muslim regimes and consider those among them who carry out violence against the "far enemy"–mainly Europe and the United States–to be irresponsible and reckless adventurers who endanger the survival of the whole movement. From this perspective, suggests Gerges, the 9/11 attacks proved to be substantially counterproductive by massively heightening concerns about terrorism around the world. The key result among jihadis and religious nationalists was a vehement rejection of Al Qaeda's strategy and methods, particularly after reactions to the 9/11 attacks and subsequent terrorism in Muslim countries brought suppression of the movement.
Obviously, I don't have any way to evaluate whether that's true, but Mueller makes a fairly good circumstantial case.
