I'm surprised no one mentioned Cicely Fox-Smith's songs; they are prime examples of songs written by a woman that stand on their own merit - as songs - and authorship is not relevant.

If a song-writer navel-gazes, he/she inevitably focuses too much on self, and then whatever he/she produces will take on his/her characteristics and viewpoints, to uncomfortable or boring levels.

A good songwriter will always put him/herself into other people's shoes, see the world more holistically and incorporate into the song more than a personal viewpoint - in that way the song can have wider appeal.