The original ending of ME3 that most people got since they played it before they revised the ending and added the DLC made a lot of people not even want to play any DLC. The Wii U version doesn't even have the option to buy the DLC. This should have been part of the main game. You don't need to finish the game to do the Citadel DLC but it should be done last right before the point of no return. There is where you will end up if you load a save after finishing the game anyway.