First of all, why Ryan and Shayne when, say, Jane and Elaine exist? It can't be the sound. Is it some kind of side effect of the women's movement - anything men can do, women can do better so let's name them accordingly? Or a not quite conscious feeling that people are socialised into particular sexual and gender roles, and that cross-gender naming can contribute to a kind of levelling-out process and a "better" society?
Secondly, if this is so, and I suspect it must be, presumably it's the women who do most of the baby naming. So, in rejecting traditionally female names they are rejecting traditionally female roles and endorsing - what? Hard drinkin', shootin', swearin', butch little toughies? Future presidents of colleges, multinationals and nations, on the assumption that there is still a glass ceiling for women who aspire to these positions?
And where does this leave the boys, who are not being named Priscilla or Rosalie? Are they only faced with more competitors in the career race, or are they being symbolically castrated as well? How would a little Ryan boy feel with a little Ryan girl sitting next to him in the classroom?
Finally, what about nuns? Not being RC I've only got vague impressions, but it seems to me that women who entered convents used to sometimes at least take the names of male saints, so you could get Sister Joseph or Sister MaryPatrick; now I think they are more likely to keep their own names. But did one ever get Brother JohnMary, or Brother Bridget?