Whether it's as an accoutrement of sapphic love or not, fundoshis worn by duos and groups of women conjure up a fascinating mix of innocent and debased associations, like no other "man's garment" worn by women quite does. Although fundoshi are the ancient swimming costume of the ama (female pearl divers), so often in the modern context a woman wearing one is doing so as a prop in some sort of fantasy.
This is what makes the idea of women enjoying themselves in fundoshi, whether in a sexual or innocent manner, so important to the advancement of the fundoshi as an alternative to mass-manufactured underwear. Because it demonstrates choice -- the choice to wear fundoshi on your own terms whether you're male or female, whether you're straight or lesbian.
Wives, girlfriends, and unattached women should be empowered within our society to do, say, and wear what they want!