HANDS: Any logic-based rationale behind their design? Or all about visual appeal?

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There are some handsets that are canonic, and have their own nicknames. Mercedes, Plongeur, etc.
And Seiko have a few "iconic" designs that they use for their Turtle andTuna; What are they called, "Harpoons"? Fugly little things.

But given that many famous hand designs are found inside diver watches, one would think they have primarily, if not solely, one function that MIGHT over-ride all other concerns.
Which is NOT to say that 'looking good' is not also their primary concern.