Why would we need better eyes, a better sense of smell, a better anything?
If you look at humans compared to any other animal in the world, we've succeeded pretty well- probably because of our better brains that most other animals don't have. We've been able to get rid of and treat diseases that could kill us- unlike other animals which don't have large enough brians to develope technology to fight other diseases.
Humans are a lot better off than pretty much everything else.