[Disclaimer: I'm thinking out loud, here. Feel free to pick holes in my theory. :-)]
Random thought about the whole "how we treat canon women in fandom" thing: I wonder if one reason why we (some female fans, that is) don't want to write women is because we're scared we'll get it wrong? There are two sides to that:
Side 1: If I'm writing a man and I get something wrong, some man can tell me and I can just say "good to know" and fix it, then do better next time. It's okay if I messed up because I'm not a man, and no matter how empathetic and observant and knowledgeable I am, I can't know down to my bones what it's like to be a man. I'm bound to mess up sometimes. Honestly, there's a good chance that when I do mess up, people might even shrug it off and give me a pass--assuming the mess-up wasn't egregious or hurtful--because I'm female. There's also a good chance that my largely female audience won't even notice. All of that put together gives me a bit of a safety net, pride-wise.
On the other hand, I am a woman. I ought to be good at "being a woman," right? I ought to know it down to my bones. So if I mess up writing a woman, that calls my gender identity, in some ways a very large part of *myself*, into question. Logically knowing that "how to be a woman" is a cultural and societal construct that varies from one location to another, one religion to another, one culture to another--hell, from one *woman* to another doesn't change the fact that pride-wise, no one wants to hear U R Doin It Rong about something that's a huge part of her identity as a human being***. Especially if, as I personally am and have seen other fans say, the person is socially awkward or not adept at/personally interested in conforming to Doing It Right (for whatever values of Right her society happens to use). Whether or not you personally want to Do It Right, you don't want to be caught on the internet with your metaphorical pants down because you don't know *how* to Do It Right.
Side 2: This whole random thought was born from reading
this post by
musesfool on my friendsfriends list. The post talks about the "catch-22" fandom puts canon females in. Reading the list of criticisms that are leveled against women in canon, I thought--But isn't that what (some) women say about (some) other women in real life? Isn't the misogyny leveled at women in canon just an extension of the misogyny some women level at each other? I don't know for certain that this is true, but let's assume for the sake of argument that it is. If so, when I write a female canon character, I'm putting her (and myself) in the firing line to have those criticisms leveled at her (and by extension, me).
Say I want to write Prentiss (from Criminal Minds) as a woman who enjoys sex, who isn't monogamous, and who isn't ashamed of any of the above. Well, that could either be considered a description of a confident woman or a slut, depending on the audience's opinion of such things. Say Fan X reads my story and decides that I'm writing Prentiss as a slut and that she needs to tell me about it. While in a perfect world (and if I were a perfect person), I'd just shrug off her complaint as different strokes, etc., the truth is that I stand a real good chance of feeling attacked. Again, I'm not talking so much about logical reaction as emotional one, so while I may know that coding a woman who enjoys sex, etc. as a slut is misogynistic, that doesn't stop the internal voice saying that I'm Doin It Rong when it comes to writing a decent woman. This is probably even more true if I grew up learning that sex-before-marriage was teh evol--which there's a good chance I did, if I grew up 20-30 years ago or more.
Say I want to write Prentiss as being not all that impressed with sex, or only interested in a monogamous relationship and comfortable with waiting until she's in one to have sex. Fan Y feels the need to tell me I've just taken women's sexual freedom backwards half a century or so. Logically, I know that the woman I just described is as "real" as the one who is all about sex with whomever, whenever ... but again, there's that *feeling* that maybe I'm Doin It Rong.
The thing is, I don't think many--if any--one wants to be called out as Doin It Rong. People don't generally want to look ignorant, uncool, or completely unable to understand how other humans tick, especially when that other human is someone ostensibly like them. No one wants to be the Fan Writer Who Writes Misogynistic Portrayals of Women, hereinafter held up as an example to all of fandom as What Not To Do. Since many parts of fandom have an excellent track record for A) using misogynistic language against canon female characters and B) *complaining* about misogynistic portrayals of canon female characters, it's not a big leap to think that one's own portrayal of a female character might get the same treatment.
So some of the reluctance to write female characters, I'm speculating, might be from fear (or maybe discomfort would be a better word?) that in some way or another, the writer is going to be found Getting Something Wrong on the Internet, something the (female) writer "should" know better than to get wrong. Rather than put oneself under that threat, it's just easier to not write the female at all.
***Probably. I have these vague memories of studies that talk about how gender coding starts pretty much from birth (if not before), and about how people tend to respond differently to males vs. to females. To me, that would argue that one's entire knowledge of the world would be influenced at least in part by (societal expectations of/reactions to) gender. People being people, I'm sure that there are some out there for whom gender doesn't really signify.