Do you think that smart phones ought to be banned because texting and playing games like pokemon while driving leads to many deaths on the roads and no amount of warnings and laws stops people texting while driving.
Maybe a "stupid phone" could be used as a substitute and a second device for apps like pokemon could be created. The second device could be engineered so that it turned off when inside a car. The stupid phone could be bluetooth tethered in the car and only work in hands-free mode. Maybe something like that would save lives.
The trouble with this line of reasoning is that it takes us to all sorts of silly places.
Maybe we should ban small children because they can be very distracting, especially to a tired driver. Perhaps we should ban drinking (liquids, not specifically alcohol) because it's hard to concentrate on the road when you're crossing your legs desperately needing the bathroom.
The problem isn't phones, the problem is that our vehicles have become little more than mobile entertainment centers and we've allowed people to get comfortable with the idea that driving is merely a period of mostly dead time that can be usefully filled with activities other than looking at the road and guiding the car such that it doesn't hit things.
Smartphones may appear to be a problem but the problem with trying to use an automated solution is that it typically comes with all sorts of side-effects. It's a bad thing for a driver to be playing pokemon while in the car but there's no reason why a passenger should not. There's no reason why you shouldn't be posting on Faceache while travelling on a train or bus, or indeed while sitting in the passenger seat of a moving car.
If someone can come up with a way that a smartphone can know that it is moving and also that the person attempting to operate it is driving a motor vehicle then by all means use something to disable certain functionality. It wouldn't work to merely disable everything because a lot of people use their phone for navigation, and it's hard to see anything wrong with having a phone, in a moving car mounted on the air vents, checked periodically by the driver of the car, when all it's doing is saying "take exit 43 and then stay in the left lane".
When the whole "if it saves one life it's worth it" reasoning comes into play it would make more sense to ban motor vehicles completely because that would save far more lives than worrying about cellphones.