[SolarNet]

I think his point was, that in general, even the terrible mutations like sickle cell serve a purpose in ensuring the survival of our species in the face of diseases like malaria (which if it was much more potent, or our population much smaller and closer together, could wipe us out). From an "effectiveness of evolution" stand point generating those sorts of terrible diseases is a feature of the "algorithm".

We are smart enough to face the consequences of eliminating such things, of taking control of the selection function used by evolution. The question is if we are wise enough to understand that we must be prepared for the consequences, or even understand that there will be consequences.