@hawkeye10,
I would say it's the modern equivalent of lip plates, or foot wrapping etc.
Altering the human body to suit current sexual trends is nothing new, Americans just happen to like breasts.
Sexual appetites haven't really changed much, the American perception has.
This country began with a rather prudish attitude towards sex and the accoutrements thereof.
The sexual revolution, womens' lib, gay awareness, changed all that.
In America, at least, religious groups stiffled sexual expression for so long, we think shame and disgust are natural.