My intention was to propose this as a mode that could be invoked at any time - on top of any other UI that might be on the screen presently. More complicated interactions could definitely still happen on the touch screen in normal mode. When you're stopped at a red light you can still take all the time in the world to set up Driving Directions with a more traditional interface. Only while driving, you would want to use this mode for quick, rough interactions.
My intention was to propose this as a mode that could be invoked at any time - on top of any other UI that might be on the screen presently. More complicated interactions could definitely still happen on the touch screen in normal mode. When you're stopped at a red light you can still take all the time in the world to set up Driving Directions with a more traditional interface. Only while driving, you would want to use this mode for quick, rough interactions.
Good points though!