PN, you are spot on about that.
I think the benefits are that the results of an intensive and thorough investigation can point the Police/CPS/Prosecutors/individuals in the right direction to find admissible evidence of their own and a source of "expert witnesses", assuming they are willing to testify - of course, their analysis is already out there as you imply.
The downside is the willingness, or lack of, of witnesses to (potentially) incriminate themselves, their company or colleagues in the pursuit of the furtherance of fight safety.
Come to think of it, wasn't the precedent that was set last year to use the reports as evidence? Flying Lawyer, where are you?