Too much work is a poor excuse. However, as long as men's racing is so dominant (in general interest) over women's racing, a separate forum might actually do more harm than good to the overall discussion of women's racing on this forum. Now everybody sees the occasional women's rider topic getting bumped, people wonder what happened and click on it to see what new info was added to the thread. Same for women's races. I would make an occasional post in a women's rider/races topic, but i'm not following it that closely. I can imagine i'm not the only one. When women get their dedicated subforum, a lot of those occasional posters (in women's threads) will disappear, because a lot of regular forum goers will not click the dedicated women's subforum, but go straight to the men's subforum (maybe even bookmark it and bypass any other option). Meaning a lot of discussion in the women's threads would cease, and even the regular posters in women's threads might bail since they'd soon realise they're talking to themselves. Imagine going to a party and there are 50 guys there and 7 women. No problem, everybody's having a great time. Until the host kills the music and asks the ladies to continue their party in a separate room. The ladies would just pack up and go home instead.
The moment there is even remotely as much interest for women's racing as there is for men's, is a perfect time to split them up, just to keep things clear and orderly. But imho, it's too soon for that.