Why hasn't chemistry brought about a greater level of human enhancement(as of yet)? So, this question had me thinking, this as someone who comes from the field of machine learning. Why haven't chemicals enhanced our minds and bodies as much as was predicted in the early years?

From the 40s till about the 70s I would say, many scholars and general talking heads predicted that chemistry would not only revolutionize food, industry(which it has) but also completely redefine the limits of humans by extending life exponentially as well as give super-human like mental and physical attributes. 

Seemingly, this has not happened yet. While chemistry has completely changed a lot of what humanity does, it has never quite lived up to expectations(much like mine). So what is the disconnect? Is it that we just need more time? I am suspicious of that as chemistry is an very old field by academic standards and from what I read has been seeing diminishing returns in research. 

I ask this as someone with only a rudimentary understanding of organic chemistry. Thanks!
This is not a limitation related to chemistry, but related to the lack of understanding of the human body and mind.
There are a couple exceptions, such as the Cochlear implant (wich basically transforms a deaf person into a hearing cyborg), pacemakers, and some drugs that can enhance mental capabiliyties.