less irrelevant than the Fallen?
seems like each faction has it's own real estate on lore and reasoning, but since D2s campaign was Cabal focused, and CoO was Vex focused, the Fallen and Taken are just there cuz they could be there, for now. They at least picked a good lore reason for where the Taken are found: the Traveler's Light was once on IO, but the Light moved on and the shadows fell long on it's trail.
What I wanna know is what the difference really is between The Taken and "The Darkness", and I don't think we'll know for certain until either Gods of Mars launches or D3 comes out (cuz we know it will). Hell, I don't think we'll ever be given anything close to solid answers with this damn franchise. Love the game, love the setting, hate how phoned in everything we learn is and hate how obfuscated the bigger answers that would matter are.