I don't think it would lead to fewer users.
Being illegal, drugs do exude a certain magnetic mystique...but, that's not the main reason why people do them.
I'm not a user, but I do know people who used to take drugs.
Drugs are bought because they give users a certain addictive high they can't get elsewhere...plus, if their life situations are not exactly what would be called 'ideal,' drugs pull them out of their own selves, at least temporarily - they are given a moment's peace.