General: What is the need for throttle by wire?
 

Can't the just use the signal from the throttle position sensor on the throttle body, in a traditional throttle setup, to carryout the functions of throttle-by-wire?

Yea, but wouldn't that mean the computer can't control the throttle, like for functions of DSC when it needs to cut throttle.

cut fuel, retard ignition

with corresponding emissions impacts. If you want to have throttle control, isn't the best way to engineer it in as a variable, instead of adjusting other things that have an indirect impact?