The clock in question, aside from being an exact copy, was an example of a trademark infringement not copyright infringement. It's very different. In fact trademarks must be defended against infringement or they can be considered void.

http://en.wikipedia.org/wiki/Trademark#Maintaining_rights

If he had copied, even in just a similar way, LayerVault's logo to use as an icon (and assuming LV trademarked it) then this discussion would be pretty different.

Apple's clock was an exact copy of the swiss railway clock. In this case, the rounded corners are different, the color is different, the shadow is different, the lengths of the lines are different.

Apple's wasn't an exact copy either. (The Swiss railway clock design was nicer.)

There were slight differences in hand lengths, removal of the logo (obviously), and stroke widths.

Apple's clock design was indistinguishable from the original. This is not.

This is the essence of what is wrong with copyright law: "Apple paid $21 million for a clock design."

I believe in the value and importance of design, but the money/value ratio of design IP has gotten out of hand.

Did you read the article? They were sued over trademark infringement. Trademark has nothing to do with copyright or the DMCA.