1. Covered in my last post. Don't have the phone on when you need the radio if disturbance occurs.
2. Using the radio on-board requires attention as well.
3. Who said cell-id was the reason?! It's quite good to be able to call airfields/LZ's that don't moniter the radio or is out of reach or checking weather, or just being able to notify someone waiting when you're late.
This discussion is ridiculous. It's not like I'm alone in the air using a phone and nobody forces KMS & Co to use one either.