Title, basically. Why did clothing made from what seems like an impractical material become associated with transgressive sexuality and where did this stuff come from in the first place?
Around 1920, there was a shift in the kinds of materials fetishized in Western pornography and clinical literature. In the 19th century, fetishists generally preferred soft, "feminine" materials, like silk and lace and fur. From the early 20th century on, fetish generally refers to smooth, shiny, "masculine" materials, like leather and rubber.
Why, is hard to say. Part of it is advances in materials technology so materials like leather, rubber, and vinyl were just more common and less expensive in clothing. The materials are also suggestive of naked skin, and tend to conform to the human body, creating an impression of nude-but-not-nude to both the observer and the wearer.
Some people have suggested that the rubber gas masks worn by British children during air raids made them imprint on the feeling of rubber. That's one of those hypotheses that can't be confirmed. But there is a long tradition of fetishizing heavy protective wear in the UK, which led to the Atomage catalogs and magazines.
In the 1960s, fashion designers started looking at materials like leather and rubber. Leather jackets in particular were associated with the image of the charismatic outlaw (e.g. Marlon Brando in The Wild One). Yves St Laurent designed a black leather jacket for Dior in 1960, based on what Paris street girls wore, and it got him fired.
The Vivienne Westwood-Malcolm McLaren partnership picked up on the sexual appeal of the punk look, as well as the Atomage custom fetish catalogs and magazines, and figured out how to sell it as fashion. They opened the shop SEX in 1970.
Latex clothing had the transgressive appeal of socially-marginalized groups like the biker, the mentally ill, the prostitute and the astronaut.
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