Google isn't giving out Android source code out of the goodness of their hearts. It's a business decision. They also have decreased the amount of code that is open source if you measure things in a certain way (everyone has their bias). Since more and more Google services and apps are central to Android normally, those aren't open source. I think even certain standard apps aren't open source anymore.

We can appreciate open source software while still being aware of why it is happening. We shouldn't just be blindly grateful. That can end up biting us.