I'm sure there will be some obvious downside to these enhancements/drugs (allowing them to go with the cliche' "drugs are bad"). Honestly, though, I don't think it would automatically be bad if some doctor invented helpful intellectual/physical enhancements with limited side-effects. Another trekbbs thread brought up the advantages Vulcans have over humans. It's natural that humans would want to narrow the intellectual/physical gap (if possible).
And, despite the talk about avoiding genetic enhancements, the occasional comment about 24th century little kids taking advanced mathematics indicate that something has been done to improve the average human's intellectual capacity.