Originally Posted by
MrTophat
The same reason why the Alliance using Theramore to funnel troops and supplies into the Barrens was ignored. The same reason why the Alliance gunning down unarmed Orc sailors in Pandaria was glossed over. The Alliance are a lawful good monolith and anything outside that narrow cookie cutter is ignored and never mentioned again. The Horde are the chaotic evil monsters to play foil to the Alliance, but Blizzard can't kill off 50% of the player base so all its sins as passed on to whatever leadership is in charge at the time. Rinse repeat. Every time Blizzard has a chance to give the Alliance some backbone they either flinch or ignore it later, and every chance Blizzard has to stick it to the Horde for their crimes they just shrug and say 'and then everyone was very sorry' and change the station to whatever cartoon cosmic threat is trying to eat us now.
In short? Bad writing.