It's funny, but laws banning phone use while driving are some of the few 'activity ban' laws I actually support. Unlike seatbelt or helmet laws, I feel banning the use of a phone while driving can evenually impact public safety. How? Simple: though tragic, it really means nothing to me if you bash your brains out on the pavement because you chose to ride helmet-less and wrecked. Ditto for injuries resulting from refraining to use a seatbelt.
Provided you're an adult, I believe you should get to choose for yourself...and live with the consequences of your choice. When it comes to others' use of seatbelts and helmets, my safety while using the same roads as them remains unaffected whether those others are helmeted/seat-belted or not. As a result, so far as I am concerned, the choice belongs solely to the individual. I don't care whether or how you, as an adult, choose to endanger yourself. It isn't any of my business.
If, on the other hand, I am hit by someone who is busy updating FB behind the wheel, I am affected. Unhappily. I may be hurt or killed, and will almost certainly sustain property damage. None of those outcomes, especially my premature death, are worth you or anyone else getting to check your messages now instead of waiting until after you've parked your multi-ton guided missile. It's bad enough to have to share the road with active phone users while in my CAR, to say nothing of bicycles. Too many close calls in the car. It may be there's a reason my bicycle and I mostly ride MUPs.
As the old saying goes, your right to swing your fist ends at the tip of my nose. Please, PLEASE hang up and drive...regardless of whether the law says you should or not.