And the Wraithknight? It makes the Tesseract Vault, Lord of Skulls and Imp. Knights look like a fucking joke. At I5, the Lord of Skulls and Imp. Knights won't even get a chance to swing before being taken apart (assuming the sword is being used). And I realize the the point of the Vault is different from the others, as they are CC machines, but its still nearly double the points of a WK for something that fires a random attack, that might not even be what you need.
Well, the Tesseract is a pretty crappy super-heavy anyway so makes for an unfair comparison, and the Lord of Skulls is almost always going to have Invisibility and/or Shrouding from Be'lakor (who always goes with it) or the Grimoire for a 3++. As for Imperial Knights, yeah, I'd agree that the Wraithknight is probably better.
300pts for a Wraithknight and everyone says Eldar are overpowered, but look at some of the Lord of War options for other factions; Orks pay 500pts for an AV13/13/12 12HP Super-Heavy Walker with a pair of 7" Blast Destroyer shots that you can pack full of cheap Meks and give it an Invulnerable to make it preposterous to kill. Imperials can get a Knight-Acheron, which I'll take over a Wraithknight - 415pts for a Knight with a Str7 AP3 Hellstorm template and an extra attack? 380pts for a Knight with an 8-shot Str7 AP3 TL gun and hitting everyone in base to base with Str10 AP2 Deflagrate? Sure, these things are all Lord of War so you can only bring one per detachment, but who cares? It's not hard to get an extra HQ and 2 troops.
Bring three Wraithknights for 900pts and I'll bring Aetaos'rau'keres for 999pts and it'll become evident that being able to bring a silly giant monster in this game isn't something new that Eldar can do that makes Eldar overpowered.