Two of my favorite national parks are Serengeti in Tanzania and Mercantour in France. Both are national parks, and pastoralism used to be important in both areas. Mercantour includes villages outside an uninhabited core area, and there are no gates or park fees. In Serengeti there are no villages, except the ugly sprawl of the Seronera park headquarters. The Masai who used to inhabit Serengeti were evicted.
An agricultural economist once told me that it was easy to see if an agricultural extension service was working properly, just take a look at the farms in the area. Did they look prosperous?
By that standard Mercantour has been a success, and Serengeti a failure. Tourism has been the economic savior of the Maritime Alps in France. By contrast, in Africa you often see opulent hotels catering to foreign tourists, and really poor villages just outside the park boundaries. One of the problems with tourism is leakage, the proportion of monies earned in the tourism sector that ends up overseas. It ranges from about 55% in poor countries, to only 15% in middle income countries such as Mexico, Thailand and Turkey. There are people who have become wealthy from tourism in Africa, but it is not the local villagers.
Much of the East African wilderness was created by the Rinderpest in the 1890s. The famous Ngorongoro Crater, for example, was described by an early visitor, J.P. Farler (his account was published in 1882) as being "a thickly populated Masai district with many villages." The devastating Rinderpest epidemic wiped out livestock and wildlife alike, caused widespread famine, and made the colonial intrusion much easier. The subsequent absence of grazing animals and managed grass fires lead to bush encroachment. This in turn lead to the spread of the tsetse fly, which lives in bushland and is a vector of trypanosomiases (or trypanosomosis). The human variety is known as sleeping sickness. Since the animal variety kills livestock, large areas of good grazing land was lost and became sanctuaries for wild animals, who are hosts to the trypanosomes. This process is documented in John Ford's remarkable book, The Role of Trypanosomiasis in African Ecology (Oxford: The Clarendon Press, 1971).
The Masai see the loss of their land as an injustice, and it was. Not that they had inhabited the land for thousands of years. They probably reached the Serengeti in the 1830s, driving other pastoralists further south into what is now Tanzania. But it was still their land, and it was taken away from them.
In France, democratically elected politicians had to persuade the local population that they would be better off with a park than without it, and one of the explicit goals of the park is to maintain traditional economics activities.