John, you touched on something that has really struck me on these forums...men are much more prone to competition and contentious discussion. Men are very straightforward. Women, on the other hand, are the masters of innuendo and backhanded compliments. Neither is better, neither is worse, just two ways of interacting. Men have full out fights, then mutter a bit and move on. Women let most of their fighting happen under the surface, and hold grudges. This is not a factor in why bonsai doesn't appeal to as many women, but it could be a factor in why women don't interact on the forums or in the major competitions as much. In general, we see relationships as much more interconnected, and tend to work out our differences so that we can continue to maintain some politeness, even if it is only surface deep. Notice that only a couple of us will actually get into the difficult discussions.....(hey, Michelle! How ya doing? We need to do lunch someday, you'd be a blast to sit and talk to)
Think about all the women in the 70's and 80's, and still today, that flocked to houseplants. Our houses were full of pothos and rabbit tracks, terrariums, Creeping Charlie..... if you really want more women doing bonsai, then here's what you need to do:
1. Show more images of tropical and indoor trees. Not just banyan style, which is too masculine for many. Develop better ways of growing tropicals that have flowers, or appealing foliage. (Abutilon? A tougher strain of Serissa?) Right now, the tropicals are almost an afterthought. They are the trees that you grow when you can't grow the big outdoor trees, and you know it. They can't compete in shows with the gnarly old oaks, so give them another section, where they can appeal on their own merits. Popularize them. Women are drawn to the smaller, more delicate, indoor trees so give them a thought. When was the last time anyone held a class or seminar on shohin tropicals?
2. Get the word out. Set out fliers on growing these trees near the display, so that they have access to the information. Make sure that some decent ones are for sale in your club plant sales. Offer a study group or small side club for them. It may take a bit of time, but women do talk, you know. Make sure that fliers for your club are dropped off at the local Women's Club, and any gardening clubs in your area. Try active retirement homes, too.
Now this all may be postulating on my part, and maybe it won't work. But it wouldn't take much effort, and you may add to the body of knowledge about tropicals/indoor trees anyway. Which can't hurt. Women are more attentive to detail, more nurturing, and often spend more of the family budget than men. If you get them hooked, you will have a wider and more solid demographic for bonsai.