Malfurion is not an Alliance badass. He was never part of the Alliance, and never will be as he puts nature and druids above even the night elves. He doesn't give a damn about the Alliance. And Illidan rejoining the Alliance? Again, he was never part of the Alliance. Neither Stormrage brother has ever been part of the Alliance.
And in response to the person talking about the Alliance races being mundane and generic: I agree. Humans, elves, dwarves, and gnomes are in every fantasy setting ever, and always follow the same stereotypes. The only Alliance races that aren't mundane and generic are the draenei and worgen (pandaren don't count as they are with both sides), and are completely sidelined and abandoned.
On the other hand, orcs, goblins, undead, trolls and minotaurs (and elves, but those are covered with the alliance) are generic fantasy tropes, but none of them really follow the stereotypes. The orcs started out that way, but then they decided to get away from the bloodthirsty savages stereotype for orcs. Why didn't they do the same with the Alliance races? Because those races are boring and cliche compared to those that make up the Horde.