well, I tried driving with both hands the other day. But things changed quickly cause my right-hand had far more control My left-hand ended up being a drag. At least for me, I have far more control with one hand than with two. Whenever I get into trouble (raining, emergency turns) my left hand would usually over-react.
You guys here have to remember that driving is like walking or eating, it's all done mostly subconcously (sic?). If you have both hands at the wheel, and one has more control, you can overdo things. With one hand gripping the wheel at 12:00, IMHO, you get far better control over the wheels.
I actually don't remember how i drove when I was getting my license. But I do remember that I wasn't doing more than 30 mph, so two-hands wasn't really a factor.
Again, if you're going 100-160 mph, a little nudge on the steering wheel can have you going a greater distance than 10 mph. BMW's active steering tries to balance that but it's difficult when you, not the car, prefer to be in control.
As for those talking about fish-tailing and needing two-hands, it's pure bs. Whenever I'm in that situation, you just have to respond (opposite) to what the car is doing. That, again, requires delicate control.
As for going off road or encountering big bumps, one-hand at 12:00 naturally goes in the opposite direction of the front-wheels, giving you balance. It's much easier to go with the flow with one hand than it is with both hands trying to go straight. Turning the wheels in the opposite direction of where the car/truck is heading is better if you wanna go straight than getting both hands to steer the car in that direction. Again, for me, this all plays out subconsciously, letting me think about what to do next.
For those talking about getting smacked in the fact because of the positioning of the hand. Well, I'll have no hands on the wheel cause I'll be bailing out of the car (j/k). Seriously, I haven't come to that point because, like I said earlier, the brakes are your friend.