The map view options currently include three settings: 3D (the "over the shoulder" view), 2D (top-down), and "Auto" which really seems to just be 3D all the time.

The "auto" setting should have the map set to be 2D when you're not following a route, sort of like the mini-map you see in some video games. Have it switch to 3D when you're following a route. This is the sort of behavior you see with dedicated GPS devices like the kind by TomTom and Garmin.