I don't know what you mean by a "novel approach to villainy", but if you're hoping for something utterly new that isn't derivative of anything, I suspect you'll be disappointed. Imo, evil works best when the audience can mentally cross-reference it with something they already know. You can put a new spin on it, or add unfamiliar aspects to it such as the Aqir with the Old Gods, but to be effective I believe it must hearken to something known.

The Lovecraftian conception of evil is really one of the coolest that there is, anyway. I think WoW players get a little spoiled with it since it comes up so much (or they don't read quest text), but it really taps into something primal: fear of the dark, of the unknown, and of the uncontrollable. H. P. Lovecraft certainly brought an original imagination to this idea, but he hardly invented it. Very similar language appears in Poe before him (e.g. The Masque of the Red Death), and in Hawthorne before that (e.g. Young Goodman Brown). Given that the other main force of evil in WoW is the Burning Legion, a revision of the Abrahamic theological idea of demons, I'll take the Old God stuff every time. It's just more interesting, and so much more EVIL. Where the Burning Legion is dangerous in a military, "they want to conquer you and are super powerful but you can fight them" way, Old Gods are dangerous in an insidious, "they will make you kill your friends and betray those who trust you, just to watch you do it. You might not even be able to fight back" way. This is, of course, a matter of opinion. YMMV.