Maureen
In answer to your question what can women bring to the dojo there are a number of answers.
The first thing that springs to my mind is other women, it's my experience that Dojo with a number of women students especially of high rank find it easier to recruit and retain new female students.
Again without wanting to generalise it is a fact that women are GENERALLY smaller and less reliant on physical strength than men, in the art of Jujitsu that I teach I often use the women in my class as examples. Not because there technique is necessarily better than a big guys but because it's more obvious that it is technique not power which is working.
The next thing generally I find that women bring to the dojo is a little bit of civilisation, when men gather in male only groups there is a tendency towards macho / testosterone driven behaviour which a more even balance of gender tends to alleviate. Also generally I find women are more keen to share experience in their training and less inclined to treat it at as a competition.
However on the downside particularly as I teach in a University club where most of the students are in the 18 - 24 age range I have to be wary of the way boys tend to show off in the presence of women. (I believe someone once said, Men go to war when women are watching)
Finally for me, they bring an added inspiration, my first jujitsu instructor was a Woman and was one of the scariest people I've ever met (on the mat). At the time I was quite a small guy and I've never been much of a fan of fighting(I've developed a bit too much Hara since then) and seeing this lady not only have the skill but also the attitude that she expressed on the mat was a real inspiration.
That's it for the positive things. For the purpose of balance I feel it's important to be aware of some of the negative sides. Again please excuse these are by necessity generalisations.
Some women who join martial arts not only want to be treated differently to the guys they expect it and this causes tension (they don't usually stay).
I have had and am aware of other instructors who have had problems with female students who seem more keen on being 'friends' with the instructor than with training.
(I'm sure this is also a problem for female instructors with male students also)
However as I tried to say in an earlier post I find that seperating students into Men and Women is only as usefull a way of describing them as saying Big or Small, committed or less so or any other number of ways of describing the tide of humanity that washes through the doors of any dojo.