Welcome to the Alliance for three expansions in a row. Cataclysm, we got to see the great Thrall center stage as the savior of the world. He was the one front and center, firing off the Focusing Iris. MoP rolls around, oh guess what? Orcs, front and center again, this time Garrosh being the big bad, "Doing right by the Orcs!" though. Next up, WoD which was literally nothing but Orc heroes, except this time they were alternate universe and again "Doing right by the Orcs!" trying to take over our world. Another Orc hero-, and yes they were Orc heroes even if not in the AU, centric expansion.
Blizzard had 2 expansions left if they're trying to "balance things out" so to speak. Next expansion has to start with something random (Naga), end with Jaina going crazy, and the following expansion has to be centered around old time Alliance heroes which we've got to suddenly take down because they're evil!Does Blizz plan to balance out the soup sooner or later or is the Horde just a stool for Sylvannas to stand on for now on?
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That aside, yes, Alliance did get a little bit of love this expansion, but that is because the areas that were hit on were important lorewise for Alliance. The Emerald Nightmare had to have the important Druids, that meant Malfurion and Tyrande. Genn and Sylvanas got equal time with their story arcs, so they pretty much cancel each other out. Varian died and left a child / rookie leader in place, so that's why he's getting a bit of airtime, to develop him as a character.
Blizzard overall though, has trouble writing interesting story, let alone interesting story for all of their supposed leaders. There have been plenty of opportunities where certain leaders should have been in certain zones, but they were just absent. Baine in Highmountain would have made sense. The Blood Elves and Night Elves being more present in Suramar. That's just from this expansion. Gnomes would have done great way back in WotLK when there were clockwork gnomes and the curse of flesh, but nope, nothing.