Well that's a shortsighted way to view voice. You don't have to use audible feedback alone. Combine aural, visual and tactile feedback and you have a much more efficient means of control.
For example, in the carputer I designed years ago, I could see the information on a small LCD screen, I could hear it with text-to-speech, and I could feel it with vibrations from motors in the steering wheel. I could also give feedback by speaking commands or entering them on a small keypad. So I could switch between fast visual feedback or multitask my visual road input and audible computer input.
For example, in the carputer I designed years ago, I could see the information on a small LCD screen, I could hear it with text-to-speech, and I could feel it with vibrations from motors in the steering wheel. I could also give feedback by speaking commands or entering them on a small keypad. So I could switch between fast visual feedback or multitask my visual road input and audible computer input.