There is an ancient myth in our culture that men and women belong to "opposite" sexes. Based on this myth, our culture assigns men and women – and masculinity and femininity – to opposite qualities and characteristics. Under this paradigm, because men and masculinity are strong, women and femininity are weak. Because men and masculinity are rational, women and femininity are irrational.
This model is not only flawed, it is completely wrong. If masculinity and femininity were opposites, why (and how) would they be expressed in differing degrees in each individual? Most men have some feminine traits to some extent, and most women have some masculine traits. The reason these traits are assigned a value according to sex is that they are expressed more often and to a more intense extent in one sex than the other. Many of these traits are influenced by hormones, and everyone has them. For example, men usually do have greater physical strength than women, thanks to the upper body muscle mass induced by greater amounts of testosterone. However, it takes great strength to give birth, not to mention the other aspects of strength women show – endurance, flexibility, courage, etc.
The "opposite sex" model is not biological, it is political. Notice that in every case, masculinity is assigned to a higher value. It is a means to support and perpetuate a patriarchy that disempowers women and enables a monopoly on power for men. It's time to subscribe to a new paradigm. Men and women, masculinity and femininity, are complementary and equally valuable aspects of our humanity. Both are necessary to be completely human. And femininity should be celebrated and enjoyed by feminism and feminists, just as masculinity is in our culture.