So board at the conference.
Jun I think that you might have a mono operation bias in your second poll (mono method bias) that threats it validity. I say this as there are several possible groups were there is not a hakama to rank level, correlation - strictly. So, it is a real possibility that individuals in some groups would say that, 'regardless of gender and rank [nearly] none should wear a hakama in aikido.'
In my opinion, if a person wants to wear a hakama, more power to them...