Can you imagine a full-screen Weather app (in its current
incarnation) running on the iPad? Or a full-screen clock or
calculator? Weird, right? Of course, Apple wouldn’t do that.
They would have to improve on those apps to make them do more
to better take advantage of the large screen. But doing so
would actually stray from the purpose of these utility apps by
adding complexity where simplicity is desired. In short, most
utility apps don’t have any need to be any larger than they
are on the iPhone.