People have been giving girls traditionally male names for a long time, though it may be particularly trendy now. As others have stated, women are traditionally seen as weaker and inferior, whether we like it or not, and it is much easier for a girl to adopt a boy’s name than vice-versa. In short, we feel more comfortable (as a society) with the idea that a resume could appear to represent a male and have a woman (hopefully a pretty one) show up for the interview - that would speak well of her. But if we assume someone is a female and a man shows up for the interview, most people will think less of him. I certainly wish this were not the case! But baby names are just the tip of the iceberg, here, so it’s not really surprising that people are keen on naming females with male names but not males with female names.
That said, I’m pretty confused about some of the uproar here. Nothing is black and white - especially not gender expression, especially not over time. If the name [name_u]Ashley[/name_u] once implied a male and now implies a female… that’s that. Same can be said of the color pink for boys. To insist that names reflect their original gender/culture when the expression of masculinity, femininity, and cultural references change so much over time seems conformist, limiting, and at best, silly.
Furthermore, to suggest that gender-neutral or otherwise ambiguous naming makes things more “difficult” just plays into the idea that male and female are the most basic, natural things about us, and say the most to the outside world about who we are as people. I realize some may think this is so, but I strongly do not. Yes, there are differences between the sexes, but in almost every way these differences apply to the group averages, not individuals. (E.g. not every man is physically stronger than every woman, not every woman is more sensitive than every man.) We should value femininity as well as masculinity in both men AND women. Also, many people do not identify with one gender or either gender, so we should not be excluding that reality.