Briefly review the history of Azeroth again, we find that Union had been eating turtle. Stormwind in the "Warcraft I" in the Orc was razed to the ground. To the "Warcraft III", the plague of Lordaeron has been destroyed, people have become brain dead remnant of the blame; their high elves allies besieged by natural disasters and looting, the energy source has been corrupted; (and this is also the survivors of two sets of people have joined the Horde!) dwarf the capital suffered a crisis of radiation; dwarf kingdom was split into three terrible civil war. Union has not been destroyed even a miracle.

However, a different perspective to it, in fact, these human beings is still not fared so unbearable - at least they have a planet in. The Orcs had destroyed their homes, now is the devil take the floor. See Orc: They almost everyone cursed by the devil sera. Look at the "Warcraft II" ending: surviving orcs trapped on Azeroth Fengyun alien, they were completely defeated, demoralized, was also locked up in a human collective shelters opened years.