Your decision to grant read_stream and user_group only to Facebook-branded clients on platforms where Facebook is not already available seems legit, even though I don't know any client or platform that is not supported by Facebook yet.
Nevertheless, it makes me sad to see that this decision will kill my app Play'em. Indeed, the point of Play'em is only to play videos shared by our Facebook friends, so it's a novel way to consume Facebook news. In my opinion, my app is not a threat for Facebook, nor its users. It's the contrary. It's a missing feature that I'm providing for free, without storing any information from Facebook!
That's why it makes me sad that you're killing it.