These are the same reasons that the United States has succeeded. The political and social rights that the common people have, is directly linked to the Political and social success of the society. If a man knows he has no stake in a society, he will not want to contribute to it; he will be selfish. However, if one knows that with a little hard work and determination their voice will be heard; moreover they can even become part of the ruling class, they WILL be more motivated. A society with the most motivated people running it WILL be more successful. The economic, cultural, and intellectual components of a society will be hyper successful, when the persons with the most merit achieve the highest positions.
The more so this is true, the more successful.