But Airbus has not been granted access to the FDR in order to prepare a legal case, has it? It's simply because, as the manufacturer of the airframe, they need to ascertain whether or not there is a defect in the design that could cause more accidents. Are you seriously suggesting that such data be withheld until the trial is complete?
Even with the data that has been released, there are those on here that continue to insist that the zoom climb to stall was uncommanded despite the FDR data proving the exact opposite. Even if the raw data was released to the families, they couldn't do much with it. They could try sending it to the NTSB or AAIB who would in all likelihood tell them exactly the same things that the BEA are saying. The trial wont begin until the full report is released in any case, at which point all the relevant data will be in the public domain.