No one is asking for a page of page adaptation. But having Mystique and Magneto again in prominent films after siX films is too much. I doubt you would see a lot complaints here if Storm, Nightcrawler, Beast, Cyclops have already done so much in the previous films. Or if Psylocke, Angel and Jubilee weren't wasted in favor of Magneto and Mystique. But that's not the case, and people are once again not liking the possibility of that happening again. And we shouldn't be grateful that Beast and Jean might be doing more this time, its quite an overdue since Jean has been in the films since 2000, while Beast's first appearance was in 2003. A lot of these characters should have been as developed as Logan and Xavier. X-Men is not the Magneto, Xavier and Raven show.
As for the First Class cast, First Class was the lowest grossing X-Men film at the time in North America. And the real draw in Dofp was the Ot cast returning together after eight years, not because those FC actors won or nominated for something. If the First Class cast was that precious, Apocalypse should at least opened just as big as X3 (you know the film that the ot cast headlined and the film that is called as "worse than Apocalypse"). But they couldn't convince the audience to watch Apocalypse regardless of their success outside of this franchise. I doubt that's gonna change next year when Dark PhoeniX gets bad reviews.