As for why more women don't ride, I can't answer that question. Maybe they're intimidated by the power of the bikes, safety issues (probably a big reason), their SO doesn't want them to ride, and so on. I only know why I ride and the i satisfaction I get from riding.
There are some people who are truly not meant to ride.. Whether they're just stupid enough to ride outside their limits or cannot physically handle the bike, it's just not meant to be. I watched a beginner MSF class one morning while my bike was being serviced. There was a gentleman taking the class who just could not get the feel of the bike...and this was a beginner class. He finally bailed 1/2 way through the class. He was devastated, but he realized it wasn't meant to be for him. Will he go back and try later? Who knows.
When I took my class, I had never ridden before and passed. There were three who did not, including a gal who had been riding for three years and who had ridden her Harley to the class from 120 miles away. Will she stop riding, probably not.
As a mother, I was very nervous when my son started talking about getting a bike after his last deployment. We talked at length about riding and bikes on numerous occasions. He finally decided he really wasn't sure he wanted to ride. Would I have been worried about him....oh hell yeah! What parent wouldn't be? A beginner rider and out in California...yikes!
I think it's great that women are riding, and I would encourage more women to at least try riding. How will they know if they don't at least try? It's wonderful if they have a good support crew to help them out as they learn to ask questions of and help them through when there are issues. Things are going to happen and some are much more serious such as the situation with Infidel's wife. Thank goodness she came out ok. She's got a loving husband who will help her work through her decision to ride/not ride. The end decision needs to be totally hers, though.
There is nothing wrong with a man being protective and old fashioned. In this day and age, it's nice to know there are guys still out there like that.