That's the cosmic horror part of all of this. We could end up creating robots that act completely like humans in every single way, except they lack our subjecti

That's the cosmic horror part of all of this. We could end up creating robots that act completely like humans in every single way, except they lack our subjective feelings of existence, embodied emotion, etc. which is presumably bad. It's a bit difficult to state why sentience is better than non-sentience but the idea does seem kind of depressing. Philosophical zombie is the term, incidentally.