Easy. The wreckage was only 115-130 deep in the Ocean. It was too easy for anyone to reach and research themselves. They couldn't leave it there so they had to bring it up so they could control access to the crime scene. Had it been in deeper water that was not disable except with much more sophisticated equipment and lots of expense, then they could have declared it a cemetery, controlled access, and be done with it. But this was just too shallow, easily reachable with minimal equipment. They had to bring it up and "fix" it.
Easy is right! And no excuse for my not figuring that angle out for myself.