I don't think it is - I didn't define what I thought were masculine or feminine characteristics. Your counterexamples from your experience (skirts, for example) aren't necessarily feminine characteristics anyway: kilts, long hair and jewellery (earrings and more) have all long been worn by men.
I also didn't say that "more" masculine characteristics are more attractive; all I'm saying is that prescribing a new norm for men or women does not in any way mean that hetersexual men or women are going to stop finding the base masculine/feminine traits less desirable.
Desire is not just instinctive. To continue the example: a skirt, long hair, and jewelry can conform to either masculine or feminine standards of attractiveness, depending on who, where, and when you ask (and on the specific styles of said skirt and jewelry). Desire is rooted in instinct, but "nurture" clearly plays a huge role in shaping it.
I think it's perfectly reasonable to consider the possibility that "women's expectations of masculine behavior have changed in 30 years." The underlying instincts of romantic/sexual desire don't need to change for this to happen.
Another example: facial hair is a secondary sex characteristic for males, and indeed we see that facial hair on women, is relatively universal at reducing attractiveness for heterosexual men. However, the "most masculine" big bushy lumberjack beards are rarely the most attractive, and desirable facial hair across cultures and times has varied greatly.