If you are going to have rules surrounding driving (speed limits, stopping at red lights) then it would make sense to address other actions that can cause harm to others such as being on the cell while driving.
While I'm against rules that don't impact others such as helmets for cyclists and seat beats, I'm all for reducing the number of reckless folks on the road.
Incidentally, I'm not against using safety devices and would use them with or without a law. Just don't think the law should force you to do things for "your own good". If you don't want to wear a seat belt and get killed as a result, that's on you.