Because really simple brains don't have consciousness, they aren't sufficiently powerful enough to have the "mental machinery" needed for consciousness. We kno

Because really simple brains don't have consciousness, they aren't sufficiently powerful enough to have the "mental machinery" needed for consciousness. We know that brains can implement things like theory of mind, self-awareness and abstract concepts; these particular things don't require a human mind but they do appear only in animal brains above some level of complexity, and don't appear in brains so simple that we'd have the power to simulate them in 2020.