That's what Apocalypse does though. And you couldn't call a movie X-Men: Apocalypse (or even the originally considered Age of Apocalypse) unless there was some sense of there being an apocalypse.
Which of course begs the question of whether Apocalypse was the right choice of villain in the first place.
The amazing opening sequence suggests he was a good choice and that there was huge potential in the story, but of course it was never satisfactorily achieved through the rest of the movie.
There could have been other ways of telling the story. For instance, have his original horsemen entombed with him and awakened with him. He could capture Magneto and attempt to possess him, or siphon off his powers (like the Zaladane storyline) to cause world destruction. Just a few thoughts off the top of my head.
And, of course, this ominous box office performance makes my call for an Extended Edition Blu-ray look more and more likely. They'll neeed to recoup that cash! A longer cut already exists, as the theatrical version was the result of editing that down...