I have an impression this is an approach similar to that of Microsoft.
Microsoft has money from Office and Windows so it can afford to make and try to sell various risky things, like Xbox, zunes, Surface RT. They even might be made at al loss, if necessary, just to see what remains stuck on the wall after a while.
Google is well known for a number of its initiatives beyond search, most of which were failures like Wave, or Google TV, but some were reasonably successful (Google Docs, for example). They never tried premium hardware (Nexuses are sold as cheaply as possible), so its an attempt to see if they can win something from that.
After a while we'll see if market approves this. My feeling is that it will have similar fate to Google TV or whatever like like that unfortunate hardware companies like Logitech tried to adopt. Probably, it doesn't have a real business plan, its an experiment, maybe not that costly for Google, because an outsourced manufacturer in Taiwan or China or maybe some Motorola division assembles the thing for them, its kinda experimental.
The thing is that after a number of such tries in various fields (Glass, TV, music, etc) none of which really add to their core strength of selling private information for ads, they will begin to lose more and more money. Since their search algorithm made 15 years ago, they have really nothing innovative, all their recent attempts - android, g-drive, picasa, whatever is still aimed for data excavation from individuals.