Why? What is it about this whole "DLC is inherently bad" mindset? If the game is released completely and finished, then everything should be fine. Not only would DLC give developers the chance to give us players scrapped content (Worlds, Keyblades, Summons, Attractions, etc.), but it also supports the game for a longer time instead of just being all "well, we released it. Go play now. That is all."
If you don't want to buy the DLC, for whatever reason, then there shouldn't be any need for you to be mad. Just ignore it.