You're confusing developers with publishers. Developers love this shit, one simple API that's built in to the OS and you can support payments worldwide instead of having to integrate with dozens of payment providers all with their own quirky APIs.
Now for publishers, who want to maximise their profit margins and who don't have to actually write the code to do all those integrations, that's a different story. But I don't think there is a single developer in the world who enjoys integrating with 3rd party payment services.