From a Time article highlighting how "Chevy [has] tweak[ed] its SUV for the stiletto crowd*":
"Nowadays, gender-neutral looks are being paired with woman-friendly modifications so subtle that men may not even notice them...."
Here, the implication is that a company should not modify its products unless the changes are so subtle as to go unnoticeable by its regular (that is, male) customers. Reading between the lines, there is also an assumption that if men knew that a product had lady features, they would not buy that product, hence the need for "subtle" modifications.
Many products are designed for men and/or those who do not wear the costume of femininity like, say, high heels, thus posing a functional problem for many. Yet, when products are designed with the male consumer (or non-high-heeled lady, but really, the male consumer) in mind, there is no need for subtlety. It is, after all, the default. Invisible in plain sight.
*Note: The wording of the title differs between the print article and online version.