When I wrote my own rulebook (about 320 pages), I made sure to only include "he" and not "she". I could read a book that only said "she", but I think it'd be jarring; I was taught that "he" was essentially used in the general sense, and unless we're referring to a specific person, to use "he" over "she".
Seeing "he" and "she" didn't bug me (in any sort of real huge way) in the 3.X PHBs, etc., but it kinda seemed forced, in a way. I'm not sure how to describe it. A lot of the time it felt natural, but sometimes it just stood out.
Anyways, I have no intention of using "she" (in the general sense) in my own rule book over "he". That has to do with how I was taught to read; my first reaction on reading "she" is "she who?" So, to me, it's not general. Admittedly, if I was reading a rule book where that was the case, I think it'd be less jarring after I got used to it.
For me, this is more a matter of "I've been trained to read this way, and breaking this pattern means it makes it harder to read things." Am I okay with "she"? In a moral sense, absolutely. But, honestly, it makes it harder for me to read things (until I adapt to it), thus my preference for "he" in the general sense.
Side note: I'm okay with "they" as a second choice, because I tend to use that word verbally (though I guess I'm more formal in my reading / writing habits). And, as I said, I'm okay with a mixture of "he"/"she" when linked to examples; when I think "she who?", the book will provide an answer. Win/win, as far as I can tell.