Two related stories.
Microsoft's Windows Store is a mess. It's full of apps that exist only to scam people and take their money. Why doesn't Microsoft care that their flagship app store is such a cesspool?
It's now been more than two years since Windows 8 was released, and this has been a problem the entire time, and it is getting worse. If Microsoft was trying to offer a safe app store to Windows users, they've failed.
Flappy Bird wasn't the first game to spawn an entire ecosystem of me-too clones, nor will it be the last. And now that the developer of the insanely difficult but addicting game has released the even more insanely difficult and even more addicting (is that even possible?) Swing Copters, well, we're seeing it again.
This applies to all application stores. They are filled to the brim with crapware nobody wants, making the experience of using them pretty unappealing. Since Apple, Google, and Microsoft care about quantity instead of quality, I don't think this will change any time soon.