It's just the easiest to discuss. Everyone can have an opinion on color, even if they're not technical. Personally, after playing with it for a bit, I think the camera is the most exciting asepct of the device, but it's not nearly as entertaining (or easy, or contentious) of a subject

It's a sign that the product is mature.

Desktop PCs used to be beige, or rarely black. Now they come in colors with LED lights, and all kinds of decoration.

Cars used to come in black, now they have colors.

It's like that for everything - at first you just want the thing for the functionality. Later you also want it to look nice.

I've sometimes waited to buy a new gizmo till I see it offered in colors - that's my sign that the product is "finished" and is as good as it's going to get. (It's true for games too - do you know games where you can change the color/outfit of the character?)