(Side note: I wonder why there are fewer female directors than other areas of production?)
Hard to say. To their credit, the producers of the modern Star Trek shows, who allowed lots of their cast and crew members to try their hand at directing, included women among the novice directors -- notably Roxann Dawson, who's gone on to a pretty steady career as a TV director (as well as a producer on Crossing Jordan and Cold Case).
Another area of prime-time television that interests me--tangential to SF--is the animated comedy. Does anybody know if any women write for or produce The Simpsons, Family Guy, South Park, Futurama, American Dad or other such shows?
I saw a number of female names in the producer list for The Simpsons on IMDb, but there don't seem to be any currently. And there do seem to be some female producers on Family Guy as well, which startles me given how misogynistic that show seems to be.
Come to think of it, there are some prominent female directors in animation these days, notably Lauren Montgomery, who directed the DC Universe Wonder Woman movie and co-directed Justice League: Crisis on Two Earths. Also Lauren McMullan, whom I often get confused with Montgomery because of the names, directed a number of The Simpsons and Avatar: The Last Airbender episodes, among others.
For that matter, the voice directing field in US animation seems to be overwhelmingly dominated by women: Andrea Romano is tops in the field now, but there's also Ginny McSwain, Susan Blu, and Mary Elizabeth McGlynn (who works mainly in anime dubbing).