Also, there was/is a Svartalfar mod by Sureshot, which not only makes them playable, it also adds lots of new units (with new art) to them and makes them an imbaabuseomg race (the last point being subjective ;p)
Remember that races are unplayable for a reason, and that reason is normally not "We hate our players" but "the race doesn't have anything interesting to it yet". This is a random guess I'm pulling out of my ass, but I think that the DARK elves might receive some attention during the SHADOW face.
Btw, I'm curious where exactly Kael took the name from. Being German I have no problem understanding "svart alfar" (black elves, literally), but I'm pretty sure Kael didn't just make that up with a vague knowledge of Germanic languages. Also, the Ljos Alfar must be forest elves with a slightly different etymology. I'm suspecting something Slavic, since the Polish word for forest is "las".