ok so, what they did was they showed us concepts featuring highly draconic and demonic amazonian looking characters, some that were made smaller were made to looks more succubi while those taller looked more dragon like, in the end they chose some features from more humanoid designs to create the au ra that you see now.
during that time a lot of people hated the fact it was a quote "human with dragon parts slapped on" since they felt the concepts of more beastial dragon like au ra was replaced with "a more kawaii design" a lot of people were also put off by the sexual dimorphism between males and females. (yet i bet the same people who argued for no dimorphism would want it for viera in the reverse)
some images of said au ra concepts: