What I mean is that they're using their voices to create sounds that convey the emotions they want. I find it much more authentic... anyone can read/sing lyrics. In these songs, you can feel what they want you to feel, regardless of what language(s) you understand.
The only male singers I can think of right now that do that are Trent Reznor(a little), Bob Dylan, and Eek-a-mouse (reggae artist). I'd say that it would be accurate to extrapolate the generally accepted idea that most female bodies are usually a lot more appealing than most male bodies, to voices. Does that account for the huge disparity? Most of the music I listen to uses female vocals in some form, and I can only name 3 artists that use male vocals in somewhat the same fashion.
Maybe I'm just too doped up on nyquil to think straight?