What you cite is a fact, but you take it very much out of context. Wind Installations have been cheaper in the US, because they have been located where the wind blows constantly, this isn't the case for Africa and much of the developing world. You cannot take that data and generalize it to other countries, or other places in the US. In some locations wind will provide even greater benefits, and in others it will not. Also, and importantly, these costs are based on having an reliable base power generating grid. Wind can be extremely expensive when it is the base supplier since storage is required to provide power when the wind isn't blowing. Wind cannot provide more than a small fraction of the total power except in a few places on earth assuming having power 24/7 is part of the equation.