Since impulsivity, whether it be emotional (flying off the handle with little or no provocation) or action (doing or saying something just because it popped into your head), is a big part of the diagnosis of ADD, if and only if it interferes with the person's ability function in daily life, the threshold of that criteria being defined, for the most part by the patients themselves, to some extent, we already have drugs that do some of this.
As far as the rest, it could conceivable make a population less susceptible to abuse of power, because they might be more alive to the harm done by it and more willing to take risks to stop it.
I have less objection to the concept of such drugs and their use because I view it rather like debating how we would have to revise traffic laws and the transportation infrastructure to accomodate flying cars. We don't have real, functional, flying cars, or real smart drugs, or real morality drugs.
I'm more concerned about the proper application of existing psychoactive drugs. Being a consumer of such drugs which, to put it bluntly, keep me from killing myself, I know by personal experience that the wrong drug or the right drug at the wrong dosage can have the opposite effect of what is intended.
The same problem exists with drugs that are not psychoactive. The there are large numbers of drugs which in most people reduce the risks of fatal disease and thus extend lifespan, but can cause fatal disease in a subset of patients. While there is a way to test your blood and see if the cholesterol reducer that should protect you from heart failure is sending you on your way to liver failure, there is no objective test to confirm that a psychoactive drug is not doing more harm than good. This makes an unskilled, improperly educated, or simply stubborn doctors who won't listen to their patient much more dangerous.
In the case of misprescribed "morality drugs", negative reactions would be potentially disasterous. Drug-induced sociopathy, or even mere apathy, in just a small portion of the population would be very dangerous.
Then there is the knotty moral issue of "bad" people who won't take the drugs. Take a hypothetical serial rapist, pedophile, or child abuser. Don't we have a moral obligation to protect the potential victims from that person's behavior before the attacks, rather than punishing the criminal after the fact? But then we've violated that person's free will and personal sovereignty. As a strongly pro-choice individual, I have to defend a person's right to bodily self-determination. The same goes with schizophrenic people or bipolar people with psychotic manias who won't take their meds. You have to wait until they are incapable of making rational decisions and have become a danger to self and others. You can't do it on a preventative basis because that's a violation of their human right to self-determination.
But like I said, this is an interesting philosophical debate to be enjoyed with friends over the beverage of your choice, but to get worked up and flame-baited over it is as nonsensical as getting into a fight over speed limits for flying cars.