Any driver who is texting will automatically be less safe than if they are paying complete attention to driving only. Doing both at the same time means that the driver is less prepared for the unexpected. This has nothing to do with the driver's skill, it's just a fact of how our bodies work.
I still have yet to hear a compelling case for when a text message is so important that it overrides everything else. What if it comes in while one is in the bathroom or in the shower? I doubt there is anyone who uses texts that demands an instantaneous reply. Besides, there was no prevalent text messaging 30 years ago, and people got on with their business just fine.
But, but... doctors! And deaths and accidents! Important stuff!
People need to text to get their twitter page updated! What if that twitter page prevents someone from developing into the next Adolph Hitler! Texting while driving could prevent a WAR!
Texting is IMPORTANT! Fuck the fact that one is dividing their attention between the two-ton mass of steel they're driving at 40 miles an hour down a city street! Forget the fact that some condition could suddenly change that'd warrant full attention or two hands on the wheel!
Text NEEDS TO BE DONE for the good of HUMANITY!