Google could probably double or triple their revenue from moving in to this space (margins won't follow, but that is a different issue.)
Companies typically want to diversify how they make money, and this is very obviously something Google desperately wants given that pretty much all their new businesses are around NEW revenue streams and not advertising.
Perhaps Google want to diversify from advertising. Mobile communications would be one way of doing that.
For example, look at glass. Yeah, it's got a marketing problem now, but the tech is right out of 'Snow Crash'. Its amazing! But that damn camera on it. I have a real suspicion they are just tracking where you look to get abetter idea of what ads attract people in real life. Its only a matter of time before they have a feature that tracks your eye movement and focus to help take pictures or whatever. And then what? They know what you are looking at in real time. So what? Well, I just don't get the 'don't be evil' vibe from that kind of data.
The idea that they need to know what you're looking at to serve ads just doesn't make much sense.
Also, 'more data = evil'. I don't see that very justified. And of course, they are not sending all that you are looking at to their servers. That is practically impossible right now.
To the second: Its not that more data=evil, it's that 'evil' has broader access to you, your habits and potentially your kids and their habits, etc. I do not trust google all that much (I say this with a gmail account I use for work). It's not that I don't trust them, its that the data is powerful and can easily be used for unsavory activities. Also, practically impossible was an iPhone in 2003, but a mere 4 years later there it was. That Moore's law is really something.