The Facebook app store is a logical next step to organize the hundreds of apps that plug in to Facebook.
In order to access the apps like a Spotify or a Pinterest though you have to have to first download those iOS apps through the iTunes app store.
The strategy here must be stickiness and more sharing and awareness for Facebook apps, kind of like what the Washington Post social reader has done.
Facebook wants to become your operating system. Unfortunately Facebook rises on top of mobile phone operating systems iOS, Android, and Windows. It doesn’t own the hardware nor the software, the starting user platform.
This is why Facebook will build its own phone and mobile software.
I don’t see the day I’ll login to Facebook just to use Instagram, Spotify, or any other entertainment apps. Those apps live by themselves and share my experiences to Facebook. I may use Facebook to view that content however.
Until Facebook creates its own phone and operating system, apps within it are simply an app within an app on an iOS or Android platform. It needs a native environment with app exclusivity.