Sorry CatYaaak, but I can't allow you to let the NTSB off the hook, twice.
The NTSB does spin...off the top of my head I can think of two accidents where the NTSB proceeded with the "Ready, Fire, Aim" mentality.
How long did the NTSB persist in a whispering campaign regarding the UA 737 COS accident, floating a crew suicide theory, Boeing's freak wind rotor theory, and walking down every other blind alley only to come up empty-handed after a rash of similiar accidents (COPA coming immediately to mind.) It took eleven, eleven other 73 accidents before the NTSB came to the startling conclusion, arrived at by the Brits years before, that the rudder could hard over.
While I wasn't a party to TW 800, I know people who principals in the investigation. The FAA and NTSB, from the outset, were dead set against the missile theory. Now, if it was a missile or not is irrelevant. At the end of the day, the NTSB decided that certain outcomes to the investigation were unacceptable, and that no investigatory time or effort would be expended on "unpopular" theories.
I'm no accident investigator or aeronautical engineer. But to me, a realitively low time pilot, the "most interesting thing" would exactly why a transport aircraft, operated well within its certified limits, decided to die.