To be honest this isn't much of a surprise. While Flickr was one of the first apps to be released for Windows Phone 7 it never picked up any updates once the Lumia 800 handed the ecosystem a relatively decent camera. There's never been an update for Windows Phone 8 either, and with the increased camera technology this is a bit of a disappointment.
Yes the Windows Phone share is not as high as Android or iPhone, but it still is relatively open to have a solution to sharing high quality images from the handset with a community. Flickr is aiming to be that on other platforms, and Windows Phone could have been an easy win.
Indulged (l) and 2Flicka (r) are both alternative clients for Flickr on WP.