Maybe I'm too cynical but it doesn't feel like this was a cutesy addition by a lone engineer, it rather feels like a marketing ploy to get more people to think about using the calling features.
Google contextualizes their services to their audience, Android isn't about making phone calls, it's about 'open source'. Why? Because they need a bunch of developers to have an emotional reason to turn down the app store to write Android apps. Now that they have a competitive platform they can drop that rhetoric and focus on contexualizing Android to everyone who isn't a developer.
In human beings emotionality will trump rationality about 99% of the time, the remainder will be labeled heartless and ignored.
For an in depth discussion about PR/Sales/Marketing. http://www.ribbonfarm.com/2010/10/20/coloring-the-whole-egg-...