iPad seems to be behind on the iOS 7 curve from the beginning. My own experiences with the Betas has been that it is far buggier on the iPad. So my wild guess. What if when they launch the iPhone in September they only release iOS 7 for the iPhone. Announce it's coming to iPad later this fall. We all assume their will be an iPad event in October, so by waiting to launch iOS for iPad until then they can buy themselves an extra 4 weeks of beta. And presumably move a significant amount of team from iPhone to iPad. I doubt Apple would do this, but then i pick up my iPad and think they have a long way to go.