Most people like to stat build their subs before making them king, or at least training them. When making an Oasis king you cannot do that and stat building can be hard to some players or just frustrating in general.
Some people also want their sub to look a certain way but can't breed them/find
So why not have a sub-male creator? It will cost the same as a king maker (10 GB) and have all the same rules (One Marking free, and special eyes are +2 GB)

This can make people that breed for stats only and want a certain looking king easier to make their king the exact way they want them. This can also give others a chance to finish their current kings breeding projects or reaching any goal.