That's great, if you live in an area where it's possible to pull off to the side of the road. In many places where I live, there IS no side of the road, especially when that road runs along a ravine, or the road has trees all along both sides. It's great if you want to avoid speed traps, since there's no where for a cop to park - but terrible if you need to pull over for an emergency.
Or the side of the road is a sidewalk with pedestrians. Or you're on the highway - do you really think it's a good idea to pull over on the highway?
I'm not trying to defend people who text and drive (although "sitting at a red light" != "driving", IMO) - personally I make my wife handle all phone/GPS details while I'm driving - but I think pulling over to text is more dangerous than texting at a red light. At least in my locale.