For a long time we just had 1 main scenario dungeon and 1 "hard mode" dungeon. The reason for the "hard mode" dungeon was to fill the game with a variety of dungeons to do. We have plenty of dungeons in the game now, so we only need the 1 dungeon that adds to the main scenario now.

The experiment actually began almost 4 years ago in Stormblood where we only got 2 "hard mode" dungeons in the entire expansion, so all that happened recently was not producing the rest of them.

The resources are being put into other things like the relic areas, MM Extreme, DR and DR Savage.