As with most accidents there is a primary cause of loss (crew fatigue in this case) with the berm being a secondary factor which ultimately caused the unfortunate demise of the crew.
As with the other recent high profile loss in Canada ( Air France A340 overun ) at Toronto the fact that there was a large gully at the end of the active did not cause the accident, but was a factor in the destruction of the aircraft. Very luckily there were no deaths.........
Safety in Aviation is all about mitigating potential dangers and therefore whilst hazards at airports such as the berm and the gully exist in close proximity to the runways, incidents such as this will continue to happen. Whilst it is always going to be a possibility that an aircraft could overun, slide off the the side of a runway, land short or indeed for whatever reason get off the deck late, the chances of getting away with the incident should be made as great as possible by ensuring proper clearway's at both ends of runways and employing as much frangible equipment as possible in close location to the runway.
I am not talking about knocking down blocks of flats a mile from the runway as by this point any impact is likely to be disastrous, but ensuring there is nothing too hard to run into at close quarters to the runway................
simple really...........
