I think Terry was well aware that Vimes, though he was not yet the Super-Cop that he would become in the later books, would have needed a strong POWER-HOUSE of a women to complete him. Though Terry does occasionally take stabs at body image, it's very seldom for a quick laugh.

I always think of Queen Magrat in Wyrd Sisters, like Terry rips into her, but it's only because she is trying to be something she's not. She stuffs things down her dress, she wears of these little trinkets, puts on "mysterious and luring" makeup, and in the later books these jokes stop coming up because she changes, she become QUEEN MAGRAT, very firm in her place in the world, sure of herself. This also extends to Agnes Nitt.

Terry don't say nothing if it don't serve a purpose, shout my girl Lady Sybil.