Everyone approves of curing disease and disability, but many disapprove of what they consider 'enhancement'. Is there really any principled distinction here? It seems to me a kind of naturalistic fallacy: people assuming that there's something morally relevant about the statistical norm. After all, if most people throughout history were as smart as Einstein, the rest of us would be considered 'retards' -- mentally deficient in comparison. There's no reason to think that our actual condition is a metaphysically privileged baseline for such assessments. Really, any imperfection is an impairment. It's just that some are rarer and greater than others -- that's no reason to refuse (on principle) to remedy the rest.
Or am I missing something?