[adrianhoward]

Anyone who can enlighten me why this would be a good strategy? Seems like unnecessary fragmentation to me.

Because they optimise a particular use case, which makes it more likely people will do something, which will make it more likely that facebook can use the shared content to drive more people towards facebook.

Take photo sharing. Photos are often spontaneous. So the more responsive, quick and simple it is to take a photo and share it the more likely it is to happen. Ideally I want to hit the photo app and by the time I've moved the camera up to my face be ready to take a photo. Facebook's new app is much closer to that experience than their current generic app. I bet that it will get more photos on Facebook. More photos == more traffic == more dollars.

You can't fix the current generic Facebook app to work as a better photo taking app - since if you made it the ideal photo taking application, it would be sub-optimal at the other things that facebook want the mobile app to do.