i disagree: it seems to me that the majority of explicit and questionable heterosexual posts are quite "vanilla", and would not merit being categorised as either femdom or maledom, on account of the fact that they either:
1. do not have any clear dominant or submissive partner at all (to pick something at random, post #4363252, post #4368649, most things tagged happy_sex), even if they do have a guy on top
2. have something like a blush on the part of the female partner, or an embarrassed tag, perhaps a confident grin on the guy's face if it shows, but no significant power dynamic between the partners, i.e. something like an assertive_male equivalent to assertive_female
the tags i'm proposing would help to delineate posts with a significant power dynamic, and a clear dominant and submissive, not just e.g. be a male analogue to assertive_female. what i have in mind can be made clear by performing a search for femdom, for which the tags most commonly associated with it according to the sidebar are
dominatrix, bdsm, sadism, bound, bondage, stepped_on, sitting_on_person, strap-on, sitting_on_face, gagged, hetero, gag, assertive_female, footjob, penis, leash, whip, ball_gag, 1boy, girl_on_top, clothed_female_nude_male, dildo, sex_toy, riding_crop
which are considerably less vanilla and imply a power dynamic a lot stronger than most explicit/questionable hetero posts feature (and this makes sense to me; something like post #4441947 does show the female partner "in control", but it isn't tagged femdom because it's quite understated)
a possible maledom tag would only apply to posts if they had similarly strong bdsm themes or power dynamics, and i think it'd be useful to people interested in works like this