Why do trolls have genders when they all have the same reproductive role
Common theories for why trolls even have genders when they all share the exact same reproductive role include "it's vestigial, from when they were a sexually dimorphic species" or "it's mimicry for attracting a lusus" but maybe there is also the possibility that in addition to blood castes, there was yet another type of morphology that would determine their role in life: the morphology between soldiers and workers.
In termites and some species of ants, there are distinctions between the ones designated as the workers and the ones designated as the soldiers. Workers are smaller and they forage and manage food and maintain the nests, soldiers are larger and defend the colony.
If trolls ever had this sort of distinction (as a form of gender) then it's probably also mostly vestigial, as gender is largely irrelevant in what they are expected to do for the empire. Yet even if it's vestigial some of it still remains in the anatomical difference between (what appears to humans as) male and female trolls, and in the stereotypes and different attitudes trolls have about either gender.
