I do not understand the logic here.
Because other driving habits are dangerous too, the use of cell phones while your driving is OK? You are so wrong.
Using the cell phone while your driving is not safe. And it doesn't matter if you are using a headset either. I see it every day and there are studies to prove this.
And because people are usually too stupid to make good decisions on their own, they have to be told what not to do. That's why DUI is illegal too, even if there are more things which you shouldn't do while driving.
-H