Of course, the main complaint with the level grind isn't doing it the first time, it's doing it again and again, and thankfully, as Mystic notes, will bring us ten brand new levels to roll through. But maybe I have a bad memory, because even when I do hit 70 with a character, going back to the beginning with a new class or a new faction is a new experience. And Wrathgoing through the same content a second time makes it faster and more interesting to me -- I already know where the hard quest targets are, and I can catch up on lore or secrets that I may have missed.
Each to their own, of course -- maybe you've already leveled all nine classes to 70 and couldn't imagine going back and running through Stranglethorn Vale or Hellfire Peninsula one more time. But I've found that I almost prefer the leveling "grind" -- it seems more core to me, improving the character constantly with an XP meter, than the current method at endgame of raiding your way through the instances for gear upgrades.