Hey Kermie can you hold forth a bit on your thoughts/opinions on why Kamen Rider as a (sub?)genre seems to be so particularly male?
While I don't know
all the details (I like the shows, not the actual behind the scenes), I just think that in general, it's one of those "tradition" things. Y'know, Sailor Moon only had girls so that was that going forward, while Kamen Rider was originally seen as just one (later two) grasshopper cyborg dude against the world. A lot of the things after that just sort of… followed in those two's footsteps. Aside from that, both executives and audiences tended to associate certain themes/motifs (and thus genders) with one or the other. Oh, this is terrorism and human freedom, that's Kamen Rider, here's more "down to earth" experiences and the thrill of teenage love, those are magical girls.
However, I will note that there was
always some overlap, because at the end of the day, both Kamen Rider and a lot of Magical Girl shows are about two things— hope and the human spirit. You see that influence in things which were originally conceived as genre benders, like the PreCure series— while that series focused on "magical girl topics" like school life, those magical girls THREW HANDS.
Before more recent times when you saw more magical boys, there were also a good few females that were Kamen Riders— though you saw that more near the latter end of the 2000s. Nowadays, there's usually at least one female Kamen Rider in each series. As such, there's not really any weird gender things going on with Rei in regards to femininity/Riderism. Maybe Akemi or Himari tho, but I'm still working the specifics of those arcs out.