I can't help but think though, why weren't similar measures taken with Flight 93 (Pennsylvania, 2001-09-11) or Flight 77 (Pentagon, 2001-09-11)? I don't wish to allude to any of the many conspiracy theories, but I do find it interesting to see how a "real" crash investigation is done, as opposed to what we've been told about 9-11.
Here's a 600 page report with over 100 pages of footnotes. The first chapter deals with the hijackings. You can start your research there! http://www.9-11commission.gov/report/911Report.pdf
In later chapters, there's a lot of discussion about the terrorist group that planned the hijackings, and not much discussion on missile ballistics. That's because the former happened as a matter of fact, the latter is pure fantasy.
So what would you like to see? A detailed analysis of all of the ways the plane did exactly what you'd expect? Do you think the onus is on the investigators to disprove conspiracy theories? It's like you want a report called "Why it wasn't a missile: a detailed report on how Flight 93 looks like what you'd expect if terrorists hijacked a plane and crashed it into the ground."
You're asking others to disprove your hypothesis, for which there's no evidence in the positive, while ignoring competing evidence. This is the hallmark of bad conspiracy theories.