I'd have to bet that Nikon designed the spring contacts on the 70-200
to have enough travel in them to continue exerting enough pressure on
the corresponding contact pads in the body even in cases where a user
failed to support the lens --- besides, if you want to talk about big
lenses exerting enough pressure in what you call a poorly designed
mount to cause the problem would a Sigma Bigma qualify? I own the 70
- 200 as well, but the Bigma is a true monster and I have the HSM
version that relies on all those contacts and I have no problem - not
even when it is fully extended AND unsupported. I've observed the
mount area to see if the Bigma when fully extended and unsupported
caused any drooping --- I was only able to see that there was a very
slight amount of drooping --- just about imperceptible actually.
So, IMO if there is some sort of correlation to this problem where
the 70 - 200 is part of the problem, I do not believe that it has
anything at all to do with the fact that it happens to be a
moderately large and heavy lens that is somehow causing a problem
because the lens mount might be improperly designed. This phenomenon
has a different cause -- possibly related to the 70 - 200 but not due
to it's being large and heavy.