I see nothing wrong ethically with creating a substance that would mimic the effects of alcohol. I am of the opinion that if someone wants to take something into their body then they should be able to do so as long as it does not adversely affect anyone else. That is where it gets tricky though.
As for where PanchoHambre said that the main side effect of pot is laziness, I have to completely disagree with that statement. That is often the opinion of people who have had no experience (be it first hand or otherwise) with the drug (and I am not saying that panchoHambre has or has not had any experiences). Yes it can make people lazy, but it can also make people motivated and energized and more active then they would be otherwise, but this is really a discussion outside of the realm of the OP's original topic.