I'm not trying to say you're wrong, but I get the impression that the reason Apple doesn't have something like that is that they think it will ultimately be worse for the user experience. Frequently they seem to eschew flexibility and customizability in order to simplify the interface. You could say they go too far (though I'd personally disagree in most cases), but I don't think that they simply overlooked features such as that.
This map, though, looks like it could be part of the iPhone default apps.
This map, though, looks like it could be part of the iPhone default apps.