I think DX Wombat has a good point on some cell phone users not distinguishing between standby and off.
Just as an aside, it is my understanding that the aircraft manufacturers are planning to go to wireless for passenger entertainment and communications in the cabin. Eliminate the weight of that wiring, and just run power to the seats. And that's fine, because it will be engineered from the start.
If we want the convenience of wireless we have to be responsible for its use. Even with the concerns in a hospital, there are more uses of wireless that make information access easier and improve the experience of the patient (such as for medical telemetry, increasing patient mobility).
Maybe we need those RF detectors in the cabin.