There is business strategy involved as well. Google wants to reduce its dependency on Apple and Microsoft. Unless you were a GNU+Linux/BSD enthusiast, you were

There is business strategy involved as well. Google wants to reduce its dependency on Apple and Microsoft. Unless you were a GNU+Linux/BSD enthusiast, you were accessing their products from a laptop running the software of one their competitors. Similarly, this is one of the reasons for Android. They could have just made apps for the iPhone, Windows phone, RIM, etc, but they made apps for the iPhone and Android to help reduce the dependency and give themselves more freedom