I think what GP was getting at is that ability to suffer is an emergent property of the ability to feel pain. Sure, this emergent property may have evolved beyond this original source, but if that original source had not existed, neither would suffering.

What's not entirely clear to me is how we can create useful consciousnesses without emotions in general. As humans, we are driven by our emotional states to perform different behaviors as well as think about different things.

Maybe it's possible that we can hard-code some emotional drivers into our artificial intelligences. Perhaps we could program a consciousness to be driven by the opportunity for human advancement, and allow that consciousness to take over from their in how it wishes to pursue that goal.