First thought of mine after reading your post = why do Argonians have them?
So that "Male" and "Female" are visually obvious to the people playing the game / watching the movie / etc.
From http://tvtropes.org/pmwiki/pmwiki.php/Main/NonMammalMammariess, on TVTropes:
Prominent briasts, or lack thereof, is one of the simplest instinctive visual cues for hominids. Giving all female animals big boobs, or at least a body shape that mimics them, allows for distinction between the sixes without adding glaringly obvious costume tags, a wasp waist, or the more bizarre gender-specific characteristics in some other animals. Another reason for large boobs on Humanoid Animals is of course Fanservice.
nvde mods Any body mods at all will be a pain to do now. :whistling:
:)
(Come to think of it, having all those body shapes built into the game - didn't they say each race is somewhat different, too? - will also probably add a layer of complication onto Armor & Clothing mods. Hmmm.)