"The one thing that I don't care at all about is where in the line the wires were severed. I'm assuming you didn't run off with a length of it wrapped around your plane. To me it's six hunks of random length wire that are going to be lying on the ground to be spooled onto the salvage truck."
The on scene investgators at the time would not know whether the severed cables were significant. Every detail would have been recorded in case it became relevant at a later stage. Once the scene has been tidied up, it is impossible to go back looking for evidence, so it is vital that every detail is recorded at the time, even if it seems totally unrelated to what happened. I can speak with a certain amount of authority and personal experience on this point.
The severed cable lengths would have been measured and recorded. The copper spray contamination from the melted cables would have left marks on the outer skin of the aircraft which would have been detectable even after parts had been exposed to fire. The inner skin would be expected to display signs of copper contamination from melted wire bundles but there should not be traces of copper on the outer skin. So whether visible to the naked eye or not, the traces would be there and detectable with simple chemical testing.
Just because a full explanation doesn't appear in the official reports doesn't mean that the work wasn't carried out, simply that it wasn't considered relevant to the reasons for the accident.
Somewhere in the back of my mind I seem to recall reading about this or a similar accident being significant in influencing aircraft design by ensuring that there wouldn't be a single mode of failure in the control systems in the future. Dual paths of control were required so that failure of one system would not cause an aircraft to crash. Probably read about that 20 years or more ago, so I will have to trawl through my archives to refresh my memory.