Whoa, this turned into a computer-hater-convention real fast.
As for the first question, I was told the big reason with why we don't have steer by wire systems yet is due to weight, complexity and cost. For something this crucial, you need the system to be in TRIPLICATE according to federal regulations.
However, this type of system allows a lot of flexibility in terms of how much better a car can be driven, by the average person, in a sticky situation. For example, the stability control system (which will be mandatory on new models soon) will be able to better control steering angle, just as the ECU can better control throttle by wire systems for things like traction control.
Obviously, the better trained driver would not need this and would be able to drive the car better without it, just like many arguments about ABS. However, this is a system for the common man.
Also, this would allow cheaper manufacturing of cars due to the MUCH less complex process of mounting the steering wheel on either side of the vehicle. From a design aspect, this is very nice.
As far as throttle by wire, there are plenty of cars out there (I'm not sure any new model has a cable throttle) have these systems in place and operate fine.
For this prius guy in Ca, I believe he was afraid to shift it into neutral, not that he couldn't. At least that's what they said on the radio this morning. He was afraid it would flip. Yeah, I don't get that either.
I also think a lot of people are afraid to pop it into neutral for one big reason: liability. For example, if you bring your car to a toyota shop with a freshly grenaded engine due to you popping into neutral with the gas pedal pinned so don't lose control of the vehicle, they may try to skirt out of it since you didn't lose control of the vehicle. There's no one but you saying the pedal stuck and nothing saying you would have lost control of the vehicle. Now, if you call 911 and lose control of the vehicle instead of popping into neutral, you now have situation more publicized and toyota may listen a little more closely.
That's my personal conspiracy theory...:hunter: