According wikipedia, a corset is a garment worn to mold and shape the torso into a desired shape for aesthetic or orthopaedic purposes (either for the duration of wearing it, or with a more lasting effect).
We can learn that "originally an item of lingerie, the corset has become a popular item of outerwear in the fetish, BDSM and goth subcultures."
The strongest revivals was seen in the Autumn 2001 fashion collections and coincided with the release of the film Moulin Rouge!, the costumes for which featured many corsets.
I don't know why, it is not so bad :