I think my approach would be to emphasize to the student the
importance of situational awareness in all instances, and the
attitude that he is the one flying and responsible...I think students
(and advanced pilots) sometimes fall into the trap of
allowing/expecting too much hand-holding from ATC.

I agree with all you said.

I've been aware of this problem with ATC for a while and use it to
illustrate to students how important it is for THEM to be in charge.

I was just curious as to 1) how often others had noticed this, and 2)
who was using this information in order to descend to intermediate
altitudes.