I should clarify here that I am speaking of anime as opposed to manga. When you are dealing with anime adaptations of shounen manga where the cast is primarily male, such as Haikyuu or Kuroko, the people who will be financially supporting the anime - buying the discs, buying the merchandise, creating the fanart and fanfiction, etc. - are primarily female, and the anime production team keep that fact in mind. Even shounen adaptations with a more balanced gender ratio, such as Gintama, often have female otaku as a core target demographic.