That's long been a point of contention with the Horde, as well; with many strong-willed and iconic groups seemingly moving in lock-step with an autocratic Warchief's whims. In a realistic setting where a coalition nation of many species is united in a pact for mutual protection, it is very unrealistic that Garrosh's warmongering would be celebrated or even welcomed by a majority. Ditto as well for Sylvanas' rationale for war.