The first reason is, the draenei are a departure. While deeply rooted in the game's lore through their connection to the eredar (essentially, they are
the eredar, or as close to the original, pre-Sargeras race as one can get) this just makes them more unique, because of the setting's roots in a generic man vs orc RTS game. The other races of the Warcraft
setting - dwarves, gnomes, humans, elves, orcs, trolls, tauren, undead, goblins - all have their roots in a fairly standard generic 'fantasy' idea created by pen and paper RPG's and distilled down from Tolkien, other fantasy writers both before and after him, and the mythologies they all draw from. There's nothing wrong
with that approach - it uses familiar elements as a shared grammar to get the players up to speed, allowing them to essentially say "Oh, I know what that is" and move on. Even variations like night and blood elves are still elves
- people know what those are and can quickly adapt to their quirks. Even races like worgen (werewolves), tauren (minotaurs) and pandaren (bear people) use common tropes from mythology and folklore. Heck, even Herodotus told tales of the cynocephali
, or dog headed humans, that were sometimes believed to exist on the fringes of the ancient world.
The draenei aren't any of these things.
The draenei are, ultimately, an attempt to reverse engineer the popular, sinister Eredar of Warcraft III - figures like Archimonde and Kil'jaeden - and give us their polar opposite. Most settings would say "Okay, so we have demons, what would their opposite number be?" and answer "Angels", and that's exactly what Diablo did with Tyrael, but World of Warcraft actually did something different. It said "What if you had something that still looked like a demon - hooves, tails, horns, tendrils - but which was from a culture that valued good and the Holy Light? What then?" The happy accident of Chris Metzen forgetting that he'd already come up with an origin to how Sargeras became the Fallen Titan led to a stronger lore, ultimately, and a very strong hook for a new race. And what's interesting is how alien it makes the draenei, and how alienated.
It's not just that the draenei look different from other races in World of Warcraft, it's that they are different, and they're keenly aware of it - they've abandoned everything that made them who they were to avoid being corrupted, to prevent their entire race from being lost to madness and evil so vast it's barely comprehensible. They have again and again been hounded from whatever place they managed to light upon, hunted and nearly destroyed by those that once were their own people. Their last refuge proved to be the most horrific lie, as they were nearly totally destroyed by their neighbors, who they had offered no violence or threat to in centuries. Living among them is a Prophet who guides their aims and who speaks to the Naaru themselves, beings of living Light, and yet a hostile universe again and again threatens to overwhelm them.
The draenei have a sense of duality - they understand that there is no Light without a Shadow, that conflict is inevitable between these opposed forces. They reject the hatred that spawns murder, but accept that you will eventually have to defend what you hold dear. You can't hate your killer, but you definitely don't have to stand there and let yourself be killed. More so even than the pandaren, the draenei know balance, because they themselves stand on top of a fulcrum between opposed forces.
This backstory makes them unique in Warcraft, and more, it sets them apart from the elements of familiar fantasy and myth that make up the rest of the setting. For all the jokes about 'space goats' and 'space squids' players throw around, there's an amazing truth hidden in the jibes - the draenei are aliens. They literally are not of this world, and everything about their culture, history, even their archaeology speaks to this otherworldly nature. They subvert our expectations of what we'll find in a fantasy game in many ways - by being, effectively 'good demons', by their unusual way and mode of being, by not being elves or trolls or something else familiar to us, they blow the potential of the setting off of a easily predictable track. With the draenei in the game as a playable race, there is always the possibility things could get strange and alien again - for all that the blood elves were central to much of BC's appeal, it was the weird, alien aspect of the expansion that the draenei brought that is most commonly commented upon today by those that loved that expansion.
The draenei introduce that strange, alien aspect more so than the pseudo-Lovecraftan Old Gods, that sense of we haven't seen everything yet
. They're not like anything else in the setting, and it is still my fond hope we'll get to explore more of their story - see Argus, find out if any others survived somewhere out in the Great Dark Beyond, maybe even see a repaired Exodar ride the dimensions again. I admit, their potential hasn't been tapped yet - we've seen precious little draenei story in Wrath
, one questline in the Swamp of Sorrows
, and a saddening dearth in Mists of Pandaria
considering you'd expect Velen to be an excellent person to consult about the Sha and how to deal with them. Yet I still have hope - being draenei, you learn to keep hope in mind.
The draenei are not merely different, they are not only alien, they bring that with them into the setting. They can embrace the peace of the Holy Light and yet smash in someone's head without batting an eye, they understand contradiction and contrast in a way no other race in the setting can, because they've seen the best of their own people become the worst, watched the Legion destroy everything they value led by their own people. They are something else, and getting to play one means getting to really explore what that something else is... and has yet to be. Which is why I enjoy them, silly jokes and all.