Thanks for the feedback, everybody. In Windows 8, we wanted to provide a way for folks to view their photos on other services knowing there would be few (if any) apps in the store at launch that would do so. Now there are many apps in the store that offer ways to view photos on other services and soon there will even be a Facebook app from Facebook. We’re confident Facebook will offer great ways to view and engage socially with photos on Facebook. We welcome Flickr to do the same. In addition, the People app still offers the ability to socially engage with your friends and even your own photos.
Your statement is fine IF, and only IF, there is a way for those third parties to integrate their cloud stream of Pictures into the Photo app. If you have to open each of the third party app to view the pictures this is pretty useless and a dumb move. If I want to upload pictures and do some management, yes, then I can open the app for that request.
was one of the top 10 features of Windows 8.
This is an important point I would hope that Microsoft understand. The photos app integrated the viewing of photos from many sources (and it would nice if there were more sources), the third party app is still necessary for finer grained management of that third parties specific features. In other words, Facebook et al need to see that the photo app was never a replacement for any full featured service specific experience they would like to create.

