Ditto Stalker. Using real insects that live in colonies, I believe a 'king' in a colony hierarchy is not needed. A 'queen' is needed, however, to populate the hive/nest/colony and to insure its survival. Any male needed would be weak and expendable once fertilization is complete. Maybe such is the case in the movies where many unknowns exist.
Would the addition of a 'King' Xeno be helpful or detrimental to the franchise? Who knows, but for sheer entertainment, I think it might pass.

i think termite colonies actually have kings.