I've always wondered why. Bethesda have placed the male, female and beast bodies and textures into the world, under the floor, wherever your character has the ability to change their appearance (chargen prison cell, end of sewers), and also in Leyawiin Castle (all the meshes, including the ones in chargen are called StarkRealityxxx).

Just wondering if anyone has any idea why they're there. I can't seem to find a reason.

The only thing that would make sense is performance. They'd be pre-loaded when your character enters the cell, rather than when called for.