Why paint nudes?

This painting by Lucien Freud, 82, depicts a a life size and pregnant Kate Moss. But why does he choose to paint the naked form? In an article from 'Fairfax Digital' he says,

"I can see more: see the forms repeating right through the body and often in the head as well."

"One of the most exciting things is seeing through the skin, to the blood and veins and markings."

In an article from the telegraph, the author notes,

"Moss was an unexpected choice of subject, because he has often said that the last thing he wants is a professional model. He wants to paint a real person, not a practised holder of poses. And there can scarcely be a more practised and professional model in the world than Kate Moss"

In another interview, Freud said he painted Moss merely as an animal rather than as an icon of beauty."

So Freud wants to paint the real form, nudity revealed rather than covering up the blemishes with a makeup brush. That is why Kate Moss provides an intersting antithesis from the world of supermodel perfection to the animalistic bodily representations that derive from Freud's palette. I wonder how much space Freud requires? He is known to scrutinise his models. Does he like to get as close as possible? Would he like to paint in a shed?