Hmmm. The whole point of CRM is situational awareness. If one guy is pressing buttons, then it makes sense that he ensures the other guy knows the changing state of the aircraft. One would think the PM should simply be paying attention, but changing frequency, talking to ops/company, dealing with the CC, selecting flap, being alerted to wayward trends, reading the QRH, etc all mean the fellow may easily miss is quick stab of a button on the MCP.
I say that calling out FMA changes and the like would is entirely sensible and reasonable.