In evolution terms it would be logical if the zora eyes changed. They have eyes that are designed to look under water. If they kept these eyes if they got on land/ turn into rito they would see all blurry. I think the zora's got a little help from the gods, because a animal species can't evolve...
That could be possible. maybe the gods changed the zora into the rito because if they could swim, they would see the old hyrule under the sea while the gods wanted hyrule to be forgotten.