A better motto for Google, in three words:
Don't be stupid.
Google has Project Fi (Wikipedia article here), which offers access by cell or wifi depending on availability, through any participating carrier (currently Sprint or T-Mobile), provided you have one of the three most recently released Google Nexus phones (presumably all future GNexi will also qualify). It's intriguing precisely because it unchains the user from any one tower-mounted carrier and because you don't pay for unused data.
AT&T offers rollover data (their unlimited data is restricted to users who bundle their phone service with DirecTV), but unused bytes eventually go away. My wife and I don't generally use much cellular data except in emergencies so normally we pay for a lot of unused bytes. Fi actually credits users for unused data at a rate of a penny per megabyte, or $10 per gigabyte, which happens to be what they charge for data.
But here's where it gets stupid: to qualify for a Project Fi account, assuming you have a suitable phone, you have to have a standard Google account, with a Gmail address. A Google Apps account, which I have because I like my personal domain email address, can't (yet) sign up for Fi.
I'm already paying Google for this Apps account, and I'm paying Google to host my ak4mc.us domain. I want to be able to say (summer of next year) "Shut up and take more of my money!" so I can stop using AT&T. But there's no certainty that will be possible. Meanwhile any Gmail freeloader can sign up right now.
I went with Google Apps because I was tired of juggling multiple email addresses. I can, yes, set up a separate, garden-variety Google account to support the phone service. I shouldn't have to.
Anyway, if I signed up with Fi I'd be on a different carrier than my wife, who steadfastly refuses to give up her icky iPhone that won't work with any carrier but AT&T.
Eh, well. It's all academic for the next 16 months. Maybe Google will have figured out which ones and zeroes to rearrange by then.