This is however the only forum Iv'e ever been on thats all hush hush about gender.
I don't think what we're trying to be is "hush hush", so much as just trying to have it as "not an issue."
In the same way that a lot of people on this board don't list their birth year or their location or their occupation. They don't want those things to overshadow them (that is they're here to discuss "One Piece", not to discuss why they are a 45 year old Vietnamese male who works in manufacturing who likes "One Piece"). Does tha make sense?
And I'm guessing that on Gaia there are probably a lot of people who say they are one gender, but are actually another. I've done that myself too sometimes, and not just on forums but on "legit" sites like Amazon, CNN, Yahoo, etc – because as soon as you specify a gender, you are spoon-fed ads, stories, articles, book recommendations, etc that play on that gender stereotype. If you don't like the stuff that your gender stereotypically likes, then it's not helpful to have it all presorted like that for you.
That's only one reason not to specify a gender (or to specify the wrong one), but there are several others.