Amusingly, I've talked to many companies that are making more money on iPhone, started on iPhone, but they do all their prototyping and new development on Android simply because you can release or back out a release immediately there. Heck, it even has staged roll outs now. So there may be some design priority for Android as well if that is a common decision, since it is the better place to implement new functionality. The iPhone functionality is then often just a port.