I'm not ignoring the impact of the Clinton Administration's gross neglect of the problem of terrorism and OBL in particular. I personally believe (and it is a belief because I don't have proof) that the Gorelick wall played a major part in enabling al-Qaeda to function as well as it did, and that Clinton's refusal to engage OBL (and in particular to take him from Sudan) made the problem much, much worse for the US after Clinton left office. I also would not be surprised to learn that OKC and the plane that went down over Long Island were directly tied in to al-Qaeda, but the information that had been gathered was destroyed under the 90-day policy.
Al of that has nothing to do with the Bush Administration's destruction last year of documents relevant to an ongoing investigation of a critical national security issue.
in this case, the crime is worse then the coverup. the crime is that information was blocked and/or destroyed before 9-11, leading to 3000 dead americans in the street. the post 9-11 coverup is likely some mid level pentagon people who want to hide the fact that some of this data was obtained illegally. I strongly doubt Rumsfeld gave the order to purge it. However, if he did, I would join you in saying he should be held to account for that.
I think where we have a difference of opinion is that you say the "Bush Administration" destroyed documents, whereas I would say the documents were destroyed because of a political rot left over from the Clintonistas. The line of causation connects to the disease of Clinton politics. The only place I do agree with you is I fault Bush for not making a thorough house-cleaning both in terms of personnel in many key areas (eg: Tenet as DCI, many at Justice, many at State, Pentagon, etc.) and in terms of policy. There should have been a top-down review of all policies related to national security with the assumption of cleaning out the garbage (eg: the "wall") as soon as possible. Even had this been done, it probably would never have stopped 9/11.