found this :
The real reason most alliance think that Shaman are overpowered has nothing to do with actual game performance but has real reasons based in Western jingoism and racism. The Horde most closely mimic the archetypal dichotomy that exists between Eastern and Western ideologies. Most people that play Alliance are those unwilling to question the constructed historical geneological relationship that exists within the heart of the WOW experience. Alliance characters are thrust into a society that dehumanizes its opposition, which is reinforced by the structural settings of WoW. Note the name of Horde towns such as Undercity, and analyze the disparity between racial languages: Common versus Gutterspeak. In fact, the very names of the factions, Alliance and Horde, hold radically different connotations which privelege the alliance. This structural exploitation and denigration of the Horde faction reinforces itself by the player base it draws.
Alliance characters usually choose their race primarily on a residual self image that seeks to annihilate the non-Western other. The play characters such as Humans, Night Elves, Paladins, and Gnomes, which are all humanoid species with a slight change in features. The only few of these types who play Horde play Undead, which is the closest to Alliance that the Horde has to offer, and the only Horde race without access to Shamans. These players hate the Shamans, for they are a non-Western "other." The Shaman takes on the characteristics of the Native gurus, for he uses totems, gears himself in tribal imagery, and uses supernatural powers that draw themselves from the basic four elements. These vary same images that embody supernatural powers are the one that frightened early settlers on the Americas. These powers are not accessible to the alliance players in either realm. In real-life, their supernatural abilities fall outside accepted Western science, which is inherently reductionist, and are pagan to the predominant Judeo-Christian beliefs that are the basis for this destructive ethnocentrism. In-game the Shaman is the only class that the Alliance cannot co-opt, none of the Alliance races can be Shamans, and the only ex-race, the Alliance gateway to the Horde, is forbidden access to Shamanistic powers. Even furthermore, the most common Shamans are Taurens, a species based on cows, which were sacred to various tribes and are still held sacred to many in India. This imagery so closely plays on archetypal fears and hatreds that alliance players inherently discriminate against Shamans. Consequently, a loss to a Shaman is significant because it is not regular defeat, it is foul play, 'the Natives have cast a hex on us.' The cries of overpoweredness are, therefore, tools in the rhetorical dehumanistic arsenal of the alliance that seeks to otherize and dehumanize the Shaman by nerfing each unique characteristic. This development is analogous to the militaristic paths that Westerners have primarily taken again Eastern nations and Shamanistic tribes. The posts of Alliance players are the blankets on which the Smallpox of their nerfs is spread through our Shaman forums. This otherization creates the myth of the post-human Shaman that can destroy any class, and annihilate the inherent goodness of the Alliance. Consequent losses reinforce and reify this mythic construct and are used as tools to strengthen the hateful cries. Like Mussolini these Alliance dictators fashion themselves a 'mythic' enemy based losely on an actual figure to frighten their people and force them to rally under their banners of hatred. The shaman is the only class that the Alliance cannot coopt, and thus is the ultimate "Other" in relation to the Alliance Paladin that "cannot compete with the mythical nature of the other."