I don't have a problem with it so long as one doesn't allow it to interfere with one's driving. Now, different people have different capabilities when it comes to multitasking. Some people manage driving and talking on a phone without any problems, while some people can't handle it at all. I think it's up to each of us as individuals to know what our limitations are, and act accordingly. I do not think it is possible to make a blanket statement that no one is capable of using a cell phone and driving safely at the same time.
Some people are very capable of doing so.
So I think one's level of experience has a lot to do with it. Again, it's up to individuals to know their limits and exercise good judgment. But that's probably a bit too idealistic, so maybe they should go ahead and ban them. But they should also ban putting on makeup while driving, reading while driving, looking at maps while driving, and a whole host of other distractions. Then the problem becomes figuring out where to draw the line.