"...the Google cars look like something one buys for their four year old niece or nephew. "
They really are quite ugly. I believe that will impact adoption rate.
Modern cars are styled to be aggressive because that's what sells. The Google car is almost certainly designed to look harmless, because they want people to be comfortable riding in it. My late grandmother, for instance, refused to buy a car that had an angry 'face' (i.e. the shape of the headlights).