A wrecked camera can't be used with the lenses still safely stored in your bag. Then a pro must rely on a backup camera and so on, which the pro on assignment hopefully has got available?
I'd be inclined to think a busted camera is the less worse option here.
How many photographers go out on a mission with a backup lens?
The general consensus is that a backup(or two) cameras is a requirement for pro use.
If this is the case, then a busted lens is disastrous by way of comparison .. what good to have a backup camera available if there is no lens to use it with.
So, using such rationale, a plastic mount isn't such a dealbreaker .. and in fact is probably the better and 'safer bet'
That is, if you're out in the field(and I literally mean field ... remote location with no access to lens repairing facilities!) and there is the possibility that you could damage your gear the chances that you have backup lenses is small to none. You may have multiple lenses, but they will all be different and hence inappropriate for the intended purpose.
But! .... you will almost certainly have backup camera .. maybe we all don't, but many of us do.
Also, if the only real advantage to the plastics use in the mount is for cost reduction, then a simple $1 addition of a series of captive nuts on a metal retaining ring on the rear side of the plastic mount could easily strengthen this plastic mount design.
The way I see it is that the plastic mount design in itself isn't the issue ... the use of cheap self tapping screws is(into plastic).
As has been said a few times already, the issue is that once a force that is sufficient to break one screw has been reached there is a cascading effect and the mount will break.
The use of captive nuts on a metal ring on the rear side of the plastic mount should alleviate this ...
Are Nikon really so pressed for cost cutting that they can't even employ an engineer that could have thought of that!