The X-Men are in a very dark phase. Fall of X promise to bring about the end of the Krakoa Era in brutal fashion. However, saying the Krakoa Era before this point has been anything besides dark isn't accurate. Even in the beginning, there was always a darkness nipping around the edges of things, hinting at how grim things were going to get. The Krakoa Era isn't the first time the X-Men comics have explored gritty themes. It often seems like X-Men history is defined by its darkness.
Source：https://www.cbr.com/xmen-comics-dark-origin/
