Although the main point of this article is that targeting wealthy financiers as the focal point in breaking terror's financial backbone was the wrong tactic to pursue, the thing that leaps out at me is just how brutally wrong those who mocked the idea of "root causes" continue to be.
This American Spectator piece is about as good an indictment of the idea as I can find:
Root causes are the rationalizations liberals give -- usually after the fact -- for their immoral actions or for the immoral actions of others. The paradox at the heart of the root-causes fraud is that causal theoretical explanations are invoked only after bad deeds have been committed. Good deeds have no need of mitigating circumstances.
Thus liberals find no need to explain why Bill Gates behaves benevolently, but somehow, they require a theory to explain why Montgomery, after a good deal of premeditated scheming, gained access to the Missouri home of Bobbie Jo Stinnett, strangled her, sliced open her abdomen, and then made away with her child, later passing the girl off as her own.
There's a reason "liberals" focus on root causes for bad things: it's because we're trying to stop those bad things from happening. The secret behind Bill Gates' benevolence is a lot more transparent; in the first place, it requires him having a lot of money, and in the second place, it requires him valuing certain causes which he believes need money. Explaining violent and socio/psychopathic behavior is a lot harder and in the case of terrorism, a lot more pressing than the same process for positive behavior.
As much fun as it is to cluck at how awful it is to do bad things to people and advocate a reflexive and massive expansion of force against those bad things, the central problem with terrorism is that it uses those expressions of force as a continuing rationale for committing terrorist acts. Terrorism (unlike, say philanthrophy) is not a primarily material act, as the above article points out. The money comes, because it's not hard to raise. The people come, because they're susceptible to a radical ideology. And the war continues, because our strategy against terrorism isn't much different from how two armies with traditional goals and motivations have fought for thousands of years - focused on supply lines and the perception of winning or losing as it's tied to national identity.