Of course they had a reason. But try as I might, there's no good one I can come up with that allows them put a photo behind a numeric display, but not behind an analogue clock representation, except to prevent the user from customizing that type of watch face. I would have even accepted the same kinds of limitations as with the numeric display, allowing the hands and hash marks maybe, but no complications yet. There are arguments to be made as to why they aren't allowing these kinds of things from a technical perspective. But if they can put a picture behind numbers, they can put a picture behind a set of watch hands with equal ease, there's nothing about doing the one that would make it any more frustrating to the end user for the other. They simply wanted to limit choice at this juncture.