If you actually sit down and have to think about these things, the answers aren't quite so pat.

This article is related to the first one I linked.

The letter portrays the FBI as a place where agents are thwarted from doing their job by a "climate of fear." She writes: "Numerous high-ranking FBI officials who have made decisions or have taken actions which, in hindsight, turned out to be mistaken or just turned out badly (i.e. Ruby Ridge, Waco, etc.) have seen their careers plummet and end. This has in turn resulted in a climate of fear which has chilled aggressive FBI law enforcement action/decisions. In a large hierarchical bureaucracy such as the FBI, with the requirement for numerous supervisors' approvals/oversight, the premium on career enhancement, and interjecting a chilling factor brought on by recent extreme public congressional criticism/oversight, and I think you will see at least the makings of the most likely explanation."

This reluctance to act, and desire to cover every possible legal contingency (not to mention every possible ass) may have cost lives on 9/11.

This was the actual point of the first article, but it escaped you entirely.