I concede that it will not be one hundred percent effective and that people will continue to do it. But it will be at least somewhat of a deterrent and the arguments against it just seem so weak to me.
The personal privilege argument: Ok, so you think you are good at driving while texting or cell phone use, that you personally are aware of the dangers and will drive responsibly so why should a few idiots who can't manage multitasking cause you to lose the privilege?
Even if I were to agree that you, personally, can manage it, its not you I am worried about. Its the ones that can't manage it that concern me. Even worse are the ones that think they can but actually cannot.
There is no meaningful way to distinguish between the good and the bad cell phone drivers. Ergo, yes, the bad ones have ruined it for the good. Sorry.
The it won't work because its hard to enforce argument: I think this is pure balderdash. There will be the specific deterrent at the moment. Plus of course its the publicity associated with the new law that is also so important.
Consider child safety seat laws as an example. It has taken a decade or more for such laws to become well respected. The fact that there is initial resistance for convenience's sake is no reason not to make the effort and achieve the long term result.
The it will cause people to think they are safer and so they will drive poorly argument: I understand the theory behind this and its application to passive restraints, like seatbelts and airbags. I am pretty sure I join the majority of social science people on this when I say that whatever minimal truth there might be to this claim, it is heavily outweighed by the increased safety associated with those items.
Moreover, I see a big distinction between being generally aware that you have some "back up" safety devices in your car like a seat belt versus thinking you can drive more aggressively because you and others are not on cell phones. The former is an embedded safety device that makes it safer IF you are in an accident, the latter is something that will hopefully keep you out of an accident.
I don't see how thinking there are going to be less accidents makes you more aggressive. And, whatever minimal such effect there is would be isolated and fleeting, whereas we know for a fact that use of cell phones for conversation or texting is indeed a cause of more accidents.