Lets not kid ourselves that the likely audience split will be 50-50, check out the numbers in the relevant academic philosophy departments on even on LessWrong. ... I'm suggesting the radical notion that a female reader is as good as a male reader and no more. We ought to be maximizing the readership period, not worrying about its demographics except in a instrumental sense.

But think of the meetups, man! (is essentially what's behind all white-knighting).

There are definitely men who won't join a currently-all-female step aerobics class at their gym, but pine for the satisfaction of social marching in place (I did partcipate in such a class, but only because of an existing female friend).

Without insisting on 51/49 female/male demographics (which is a slight straw-man), it makes sense to decide whether you want the environment to be attractive to most intelligent women rather than just some exceptional ones.

In slightly more detail (and I guess this is all obvious):

A group of mostly men with a few women entering has a different dynamic than one that already has a sizable and powerful female minority. My imaginary typical intelligent woman sees some of that dynamic as unpleasant, rough edges. To shave those edges down might lose something, will certainly cost something, and might be worthwhile.

I definitely don't think "all readers are equally important", but I lean toward feeling that male and female are, all else equal ("all else being equal" - the ultimate cop-out). If I have to see these readers in these comments, their quality had better be good (and this is hardly the only reason reader quality matters).

My gut feeling about LW's topics: 5% female? Possibly not caused by a perception of excessive roughness. 1%? Definitely a sign of a problem. 30% female? Probably you've been going out of your way to favor adding new female readers over male (based on my experience with women in science / programming in the US).

Then again, it's possible that a demographic shift is caused by a change in topic, or a marketing breakthrough into a demographically different market. e.g. I'm fairly sure HPMOR increased the female percentage of this site's readership.