Google only has one phone because that phone isn't even supposed to make money. It's a phone meant for Android developers both internally and third-party. Google may not lose focus from all the other handset manufacturers creating the thousands of different Android devices, but they certainly have a difficult time with integration.
EDIT: The way you are talking about 4s it would seem Apple only has a design team, once something is designed everything else happens automatically.
Actually, they are. You think the BOM hasn't changed? You think it's the exact same components being shipped from the exact same suppliers?
The specifications are the same, but the components are newly manufactured. I'm sure the BOM has rev'd. It's a mistake not to consider phones as part of their lineup which you can buy new, just because they have lesser specs and were initially released a few years ago.
I think this is an important part of Apple's strategy, which comes specifically from the way they maintain iOS, which other vendors have largely missed out on.
This is a good example of what I'm talking about. You have redefined user experience to mean something that most people will not think of. Even giving you that, look at the current iPhone setup. Leaving aside the carrier aspect, you can buy worldwide a new
iphone 4s,5c,5s,6,6plus in multiple colors and sizes.
basically 3.5", 4", 4.6" and 5.5" screen for a phone. With prices points from $250 to $1000 in minor increments. In contrast, Google has only one phone currently on sale the Nexus 5. The 'focus', 'handful of products' mantra is repeated but is not true. Frankly, the only thing missing is the stylus and adding it would cover the entire gamut.