[QuantumChaos]

I think you've hit on something very fundamental here. When the government has well targeted interventions that achieve specific goals, this can be a good thing.

But the cumulative effect of many social interventions can give the government excessive power. Even beside purely political concerns, I think we have to ask whether we prefer the random hand dealt by nature, to a hand carefully chosen by the government.

Nate Silver gives a talk [1] describing how we could design cities to make people less "racist". If this was possible, it would represent an overtly political manipulation of the populace. Chemicals probably can't have such target effects, but they still raise the question of what rights the government has to manipulate people's behavior.

[1] https://www.ted.com/talks/nate_silver_on_race_and_politics