On the face of it it seems odd that a detaching cowl can a) Sever a fuel pipe, b) damage the airframe, and, c) damage other aircraft systems (which would be?). I wonder if the primary design criteria were "the cowl will never detach" or "damage would not be expected" if it did? Remember the light-weight foam insulation on the space-suttle fuel-tanks. Detaching foam lumps were tolerated until the Challenger disaster.
On a second point, someone mentioned the safety catch system on car bonnets, in relation to belt-and-brace systems. It's worth remembering that car bonnets also have a spring on the main lock, that holds the bonnet well out-of-line with other body work making it clear at a glance if the main lock us not engaged. One would think either a spring or just gravity could be used to hold such panels open or part-open until properly locked.