But...why do there have to be more women? I'm all in favor of admitting any women whose actual musical production meets whatever the standards are, but why admit an artist/band simply because of sex? I know the argument is that female rock bands didn't get the same support from the industry as did male bands, but presumably, the ones that did succeed were the best of those bands. And -- speaking solely about actual rock - I don't see even any of those female bands that did make it truly being up there with the top 50 or so male rock acts.
I do think it is interesting that women are far more successful in country music, pop music, disco, and the singer-songwriter genre as opposed to rock. And even within rock, the further out you go in terms of heavy instrumentation versus vocals, the fewer female fans and artists there. Metal has acquired a reputation as being sexist, but there's also the joke (true except for Renaissance) about there never being a line for the women's room at a prog concert. I do think there is a self-selection issue out there in terms of musical preferences (lots of studies on that) that explains why rock bands in particular are overwhelmingly male.
In any case, I think the further we get from "rock" being a popular form of music, the more female representation there will be in the HOF over time.