JBS,
There are numerous reasons why some items still remain unrecovered off Taiwan, none of those reasons being devious. For example try sea currents up to 4.3 knts, seas up to 8m, winds up to 75knts, typhoon season, 64sq mile search area, limited assets, the list goes on. Keep in mind that there was only one specialist diving vessel with 2 divers in the bell at any one time. The seabed in that area is covered with sand waves which tend to trap objects between them, in very short time sand fills the wave and it tends to "move" on. Even some large objects were nearly completely buried and only luck enabled them to be discovered. The bottom line here is that nature doesn't descriminate based on importance of objects when it comes to what gets buried and what doesn't. Some objects will remain buried forever, the only way to find buried objects is by searching with sub-bottom profilers which is expensive and time consuming to say the least!
Not everthing is a conspiracy mate, the best people tried for nearly 4mths and simply missed certain parts. End of story.
Cheers.