I know this thread has been made before (about a year ago), but a quick search through the database rendered it old enough to start the discussion again, imo.
Scummer's topic got me thinking again; Draenei are Eredar cleansed by the Naa'ru and we all know that Corrupted Eredar control the Burning Legion a.k.a. Demons.
We've seen Humans (and Worgen/Undead), Orcs, Trolls and Elves, alle weilding the corrupted staff of demonic power, and yet we haven't seen a Draenei do it, even though we know they were technically the first.
The initial idea for warlocks was, that we could enslave the demons to fight against them. That whole thing works like a charm, so why not let Draenei re-discover it, like Human hunters, Bloodelf Warriors and Nightelf Mages ?
They could be treated the same way (lorewise) as most Warlocks and DeathKnights... with a certain degree of disgust.
And if we're going down this road, it would be great to make (for this class only) available the red-ish skin... purely optional.