Don’t get me wrong, the films mess up some story lines or do some things extremely wrong, but in the case of the original, X-United, First Class, and Days of Future Past, there isn’t much wrong. 1. The entire X-Men series has probably the most accurate and well castes films of all time. Yes including Ryan Reynolds as Deadpool and Taylor Kitsch as Remy Lebeaux.
2. The past cast of characters is basically the future set of characters. Literally they’re the same people and the chemistry among them all is superior to any other (aside from the avengers).
3. They appreciate their fans. They know that the fans of xmen, both the films and the comics know the histories and futures of these characters and they reward them. By connecting the timelines and setting up new futures and story lines they treasure the work that the originals films did, while gifting fans a more consistent and thought out series.
4. I see the prelude to the more troubles story line as I watch Hank say “what if the war is inevitable”. *cough* Apocalypse.