That's going to work great when you are driving home in the rain from a dentist visit and cannot get it to understand when you say "turn on windshield wipers".
The problem with voice control is that it requires you to know (or guess) a lot about the thing you're trying to control. When it malfunctions, it takes more, not less, attention than a touchscreen.
I've driven Teslas for seven years, and I still have no ^%$#^ing idea what I can and can't do with voice control.