As has been stated numerous times in this thread, whether you're in the process of getting rid of Google services or not that doesn't mean Google's millions of consumers are too. WP needs Google's support to win those folks over whether you like it or not. If WP dies out and you have to switch to iOS or Android wouldn't you want Microsoft to make an application so you can continue using your Microsoft services? The same goes for potential consumers who do not use Microsoft's services religiously. They don't feel they should have to switch services just to get what they're accustomed too. Not having support of major developers will be the demise of WP if they can't get a proper backing by major companies and developers.
Now don't get me wrong I'm moving all of my services to Microsoft and it's simple and easy, but people are lazy and will just continue to do what they've been doing.