Originally Posted by
Kazakov
There is no cultural aspect to most shamans in warcraft. In Warcraft Shamanism is the hability to bargain with the elements to inflict wounds or heal them. The cultural aspect is that each race will see it differently. Some Shamans will ask the elements for their help, some will impose their will on the elements. The goblin even use their bargaining expertise and work with the elements through contracts.
In Lord of the Clans, Drek'thar talks about this. He asks the elements for their help and offers things in return. Gameplay wise the Shaman is simply a caster / melee / healer but lorewise it's a much deeper balance.
There is absolutely nothing barring other races to learn shamanism. But there is also no need for it. The Orcs / Tauren - the oldest shamans in Warcraft - had no knowledge of the arcane and thus they had to resort to shamanism. And that's why the Orcs became Warlocks, it was much easier to impose their will and use fel magic than to beseech the elements for help.
The Trolls worked a much darker aspect of shamanism through their Loa gods. While the Pandaren, due to the playful nature of their elemental spirits, work their shamanism through different forms: Dances, martial arts, meditation.
As a long time Shaman roleplayer i have to say that lorewise there is no barrier for other races to learn shamanism. The only exception i'd make it's undead. But the rest could learn but have no need for it.
Humanity left shamanism / druidism of old because the elves taught them the secrets of arcane magic. And specially because they lost their vrykul ancestry. Once they had the arcane, and the arcane saved their civilization against the Trolls, they had no need to "ask" the elements because now they could bend them to their will. That didn't happen to Orcs till the formation of the Horde. And it never happened to Tauren since they never dabbled in the arcane. The Trolls are a different matter because they always had a deeper connection to the Loas.
If it was up to me the game would have very little limitations on classes.