The extra content in the Switch versions is to counteract the wait and the performance drop. It's not as much of a difference with PS4 vs Switch, but DQXI is also on PC, and if you have a powerful enough PC, you can run the game at a much higher resolution and better framerate than on Switch. Between PC and Switch, it's harder to swallow that downgrade for some extra content, since the game really does look beautiful on PC.