Is having a forced Facebook login necessarily a bad thing? Sure, the sign-up rate might only be 50%; but if it's inherently a social app, it'll pay of with a richer user experience once the user is 'signed-in with his graph'. Of course there are many apps that simply abuse the social grap for viral invites only - that sucks. But there are also apps that are just more fun - if they can overlay / provide access to the social graph. At the end: Every app attracts the users it deserves; those who appreciate it and those who don't. As an app developer, if my app is worth the trust of a social graph, I'd rather have the users that appreciate it.