Rotorblades,
I acknowledge that the jet in your example should have replied with his call sign in response to your directed traffic information, however, with respect, ENR 21.1.7 is clear, a switching call is only required if Centre will not or cannot be monitored. The suggestion that expected workload presents a situation where it cannot be monitored is a bit of a stretch as this could occur at any stage of flight in any airspace.
The reason I post, Airlaw by rumour on PPRuNe does nothing for the professional standards in this industry, particularly in the multi crew environment. The assertion that "I heard from ATC that they like a switching call" or "ATC don't really care if you give that met report" or "my mate in ATC told me that the SID speed restriction is only a traffic based requirement" can only be negative in the modern airliner CRM environment and presents significant threats to the operation through confusion and disagreement.
By the book and always by the book, If there is a problem with ENR21.1.7 may I suggest that you use the appropriate channels to initiate change.
With the utmost respect for your profession,
MHA