What you don't seem to realize is that this is the equivalent of that for connecting your smartphone to your car.
These are the equivalent of cars with built-in iPod docks, not aux jacks. Both of these standards are incompatible with each other, brand new, and controlled by companies that change/drop their old "standards" at the drop of a hat. In five to ten years, these systems will be just as obsolete as the cars with slots to fit a first-gen iPod, 30-pin connectors, and firewire level power output.
Not to mention the privacy aspects of this. The sheer amount of data that Android Auto shares with apps is a creepy stalker/advertiser wet dream (in-car microphones, GPS, car telemetry, etc).