Humanity also decided that nuclear weapons are terrible and that we should make efforts to reduce their existence to zero. How is that working out for everyone?
http://www.nti.org/analysis/reports/nuclear-disarmament/
As long as humanity cannot resolve differences thru diplomacy, which implies compromises, humanity will always seeks advantages in warfare. Did we stopped at gunpowder? Or the machine gun? No, we kept going. All the way up to exploiting the atom.
Russia, China, et al, to follow? We are counting on it. You think those countries have not thought of the idea to gain at least one upper hand over US and the rest of the world?