You gain the trust of users to the platform. If I don't want to give out my data I should be able to do just that and this argument is really huge from user perspective. Apple says if you are using GPS coordinates please tell and show the user that you do so.
There are a lot of people who don't know anything about IT and Software like my sister. She just doesn't care about such stuff. So she doesn't know who is using GPS and who is not. Hell, she even doesn't know what GPS signals really are. And she only wants to know: a) are you using my data, ask me first so I can say I want it or I don't want it _and_ b) if you are using my data, show and visualize that you are using it cause otherwise it might be that I don't know it.
I'm certain that this rules can help gain quality and help people to get an understanding for the device and what is going on _without_ having IT background.