I find the issue is threefold.
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Firstly the writers need to stop repeating the same story over and over using different actors in the Horde. First it was Grom in war 3 then Garrosh then Sylvanas and every time they have the Alliance forgive and ally up with them to save the world.
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Second The alliance is only ever reactive to these events and only ever reacts to Hordes aggression and is never pro active. Even things like Stormheim are a reaction to things like the Broken Shore and the story bend over backwards to Justify them. Not to mention the lengths the writers go to to make sure that Anduin is always perceived as on the right side of the conflict. As long as he is associated as leader of the Alliance they will never allow the Alliance to be in the wrong.
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Thirdly is the massive power imbalance, Between the super hero roster the Alliance has and the complete lack of characters on the Horde side the war has never been a believable conflict. Blizzard either need to kill off some of the Alliance roster or build up the Horde one.
The only way I can see them rectifying this is getting some writers with a passion for the Horde writing some new novels for them and develop new characters without butchering by making them lackeys of alliance characters.
Two get an expansion where the Alliance is the aggressor however without villain batting them. Simply allow old wounds reopen and spark conflict.
Let Genn go after the Forsaken for invading his kingdom.
Let Alleria go after the Blood elves for exiling the High/Void elves.
Let Kultiras go after Rexxar for the death of Daelin.
Let Night elves go after the orcs for Teldrassil.
Let the humans go after the Horde for Stormwind/lordearon.
Let the lightforged/Draenei go after the orcs for war on Draenor.
Simply stop making Alliance characters simply forget or forgive all the terrible things the Horde has done Or remove the ones who will from the Alliance. However let Horde defend it self and fight back honorably for a change. Let it lose some ground but show they are different from when they committed these acts. Show New Characters among the horde that will not go down the same path of their predecessors and condemn the acts of these crimes once committed by the Horde, but will stand for the new horde.