Thinking of it from Apple's perspective what do they gain from opening up these private APIs? They now have a new set of APIs that they have to maintain, docume

Thinking of it from Apple's perspective what do they gain from opening up these private APIs? They now have a new set of APIs that they have to maintain, document, and support. Where does the financial justification come from? I honestly don't see "f.lux runs on iOS" being a selling point for most buyers.