What? What? What? Did you not play the same game as me? Deathwing was literally everywhere. He was communing with Ragnaros on the the FIRST QUEST in Hyjal, which also happens to be the first quest you can do at the level cap. While absent in Vash'jir his old god comrades are working evil deeds there. Deepholme was is resting place before the Cataclysm, and you show up to fix all the damage he had done. Uldum you deal with him corrupting the Tol'Vir, allying with the Air Elementals, dealing with his lieutenant via the harrison jones quests. In Twilight Highlands you deal with his old gold lieutenant and the twilight cult and actually encounter him. All the raids were us chopping down all of his forces and the Dragon Soul raid was taking the fight to him.
So again what about Cataclysm made the antagonist so distant? And the BS about him being not being in any other game is bad. He was a character in lore before Arthas, Illidan, Kael'thas. Warcraft II . . .