The world became aware of the terrible consequences and that was very significant. It is remarkable that in the 70 years since Hiroshima, nuclear weapons have never been used again, most people from 1945 onwards would have expected nuclear weapons to be used in warfare reasonably soon after that, yet almost 60 years of Cold War passed without the use of nuclear weapons. If it hadn't been for the lessons both the East and the West learned from Hiroshima, I don't think that would have happened.