Admittedly, this playlist has gotten us in trouble before because we don't really do a "male vocalist" playlist to balance things out.
The strongest argument for carving this out as a separate category is that with ~15 "best of" playlists, the vast majority of the songs are male vocalists. This is most-likely influenced by genre-stereotypes (eg, psychedelic rock and hip-hop don't have many female vocalists leading the vocals).
And so, because female vocalists often carve out a unique sound of their own, we've made it a bit of a tradition to share our favorite songs in which they take center stage.
Selections by Jason Grishkoff and Sarah Jukes.