Often the wreckage itself tells a big story, assuming most of it can be found in a debris field. It can certainly say whether it broke up in the air or hit the water intact, for a start. Then you can look for bomb explosions or other types of explosions. Even the location of the wreckage would fill in large parts of the story which is currently unknown.
The interesting thing to me is how much money,collectively, are we (and the term is loose because I don't know who is paying) prepared to spend to find this wreck?
The other way of looking at the expense is "How much are we willing to pay to prevent another such disaster?" (assuming it wasn't a conspiracy of the pilot).
Malaysia and Australia sharing about 50 million dollars.
So on MH370 there might be other useful sources of data in the wreckage apart from the FDR.