Because the DLC IS bad. How are you failing to understand that a mandatory, un-cancellable extension that entirely changes the most fundamental gameplay mechanics against your will, practically permanently, is just a bad idea?

The court, remaining exactly the way it is, but bloodsuckers outside of the courtyard don't inflict the curse. Boom, the whole DLC, solved. You would still able to play Darkest dungeon, even with the court active, and you would still be able to experience the court's content, including the crimson curse, with the champions that you CHOOSE to send to the court, not every single champion that does literally any expedition in literally any area, like it currently is. How can I make you people listen to the fact that MAKING IT IMPOSSIBLE TO PLAY DARKEST DUNGEON ONCE THE DLC IS INSTALLED IS A BAD GAME DESIGN DECISION? Keep the content, just keep it within the court - like the colors of madness DLC, which is bad, but at least it does not impede your ability to JUST PLAY DARKEST DUNGEON FFS.