In a way this could be a decision to simplify the login process for the end user. Then again, if that was the case they should have supported Google, Yahoo and

In a way this could be a decision to simplify the login process for the end user. Then again, if that was the case they should have supported Google, Yahoo and all other OpenId providers. Also there seems to be no reason to completely remove the native sign up, especially since they have already made the effort to create full support for it. Guess just like the recent trend in FB, they also just want to do an experiment and see how the users will take it.