Apple has updated their App Store Review Guidelines adding a new rule (10.7) that states "Watch Apps whose primary function is telling time will be rejected."
Apple’s website states, "Choose a face and customize it however you like."
…as long as it’s one of the nine faces that Apple built into the Watch to begin with.
So what, exactly, is the problem with third-party developers coming out with new faces for the Apple Watch?
It sounds a bit like Apple doesn’t want people screwing around with their carefully thought out, and hopefully soon to become iconic face designs. They want to be sure that people – not the people actually wearing the devices – will be able to instantly recognize each of the nine built-in faces and know right away that it’s an Apple Watch.
They don’t want anyone changing the look of the face since it might confuse other people (obviously, if you spent all that money to get an Apple Watch in the first place and you actually have it on your own wrist then you already know that it is an Apple Watch no matter what the face is displaying).
So this is all about using their customers to advance their marketing efforts. Apple doesn’t want anyone messing with their public facing image.
I doubt it has anything to do with the fact that apps that only provide users with the ability to customize the faces of their Apple Watches might be considered trivial. There are lots of other trivial apps for other Apple devices.
Personally I think there are a lot of people out there who could come up with some pretty imaginative designs for new faces. Maybe Apple will loosen up their restrictions somewhere down the line after the initial buzz wears off.