I don't think it is the Appearance of the females your seeing. I think its the style of the Art and how people were sculpted or painted back then and over there.
Well I guess we'll never know, but why would they put a character on a coin that was supposed to represent the person, but doesnt represent the person??
The coins I have seen with various Caesars on them looked like the busts I have also seen of them... You sure she wasnt "a man baby"?.. LOL..