Android system for car head units

The smart phone craze has hit the world hard and anyone who is tech savvy will want to buy one. The smart phone concept works well for people on the move and want connectivity all the time. The Android and IOS system works well on tablets and smart phones but is it practical for cars?
Some car head unit manufacturers have started to make head units using the Android platform as they predict will be a trend. Having seen numerous Android powered head units I start to question if this is really practical!
Android system allows the user to download Apps (short for applications) onto their head unit but in reality in the scenario of a car one would need only the main few functions such as Radio (or satellite radio in some countries), CD player (soon to be obsolete since people are downloading songs), GPS navigation system, USB / SD card input (for media storage and playback), Smartphone connectivity to allow media playback on the head unit from files stored on the smartphone. Android OS have over 600,000 Applications available for download and only a handful would be applicable for use in the car.
Applications such as Youtube or other video archive playback apps would only work well if the car is stationary and have a 3G or Wifi connection. It also won't be practical to play games while driving and the passenger playing the games would most likely suffer from motion sickness.

I personally feel that the Android system for car head units is just over kill.