Whoaa bboy,
That is one of my pet pieves and I have discussed this many times.
It is my believe that the only time ATC is responsible for terrain clearance is when you ar being radar vectored! When on your own navigation or a direct to clnc has been issued you are responsible for terrain clearance ( obviously, when being radar vectored you still watch closely and question any rv if in doubt).
I would really like the opinion of an atc expert about this!
Many times when flying for a small outfit in spain, I would get a direct from madrid to bilboa and subsequently a descent clearance witch would place us under the grid mora for that sector, needless to say I would stay above the grid mora until established on an airway or approach procedure! Questioning the clearance was a futile excercise.
I believe, but this was many moons ago, that the US AIM specifically states that terrain clearance rests solely with the pilot unless radar vectored upon which it becomes a shared responsibility.
Again, I would really like an ATC experts opinion on this!