Well, it could be for commercial reasons. Harem stories often have an air of mystery and exoticism which can attract readers. Western women may see an opportunity to sell these stories as they can appeal to those interested in different cultures or historical settings. Also, it might be a way to challenge or re - interpret traditional views of gender and relationships within the context of a harem - like setting.
In some cases, it could be a means of self - expression. The harem setting provides a rich and complex environment. Western women might use it to explore themes such as female friendship, competition, and self - discovery. They can create characters within the harem story that embody different aspects of femininity and through these characters tell stories that are relevant to modern discussions about women's rights and identity, even if set in a seemingly archaic context.