First off, bullshit and bullshit.
Second, they weren't doing "fine" by any stretch of the imagination (unless you call a primitive society riddled with disease, cannibalism, ignorance, superstition, and cruelty good). They were fucking horrible. Stop romanticizing history.
Third, technology is absolutely essential to meaningful life. Living day to day, hand to mouth and always worrying about where your next meal comes from is nothing but the life of an animal, utterly meaningless and can barely be considered a culture. This is especially true when combined with a good political system (which the Africans, with their patriarchs, kings, queens, and shamans, never had). If nothing else, technology is indeed indicative of success, especially when it comes to survival.