Literally our entire civilization is built on the idea that humans have qualia and therefore causing harm to humans is often unethical. If we were to somehow come to believe that consciousness is just an illusion--no more than a biochemical phenomenon, and no more special than transistor switching--then we would usher in a dystopia in which any horror inflicted on people is potentially justifiable and even necessary.
The rise of LLMs is forcing us to confront this head-on. LLMs can't be conscious--they are literally just matrix multiplication. But if LLMs can act like humans and not be conscious, then maybe humans aren't really conscious either.