To put it kindly, the Fox X-films as a whole was a mixed bag. They've produced some of the best, like Logan, and some of the worst, like X-Men Origins: Wolverine, but ultimately it wasn't until the end of their run that they began to truly play with the genre but it was too late. By then the topsy-turvy nature of Fox's relationship with the films and audiences had taken their toll.
For comic readers, in particular, the Fox films rarely captured the depth and vastness of the source material by playing it safe and going with easy to understand dynamics.
It wasn't necessary for Fox to adapt specific stories - although Logan may beg to differ - but there were pivotal moments of the X-titles that were ignored to keep the plots simple. Seeing how the MCU was able to keep the stories fairly simple while not dismissing the biggest moments of their characters, it became all the more glaring when Fox missed the mark.
These omissions, alterations or just flat out fundamental aspects of the X-Men should not have been ignored by Fox and the screenwriters...
Learning to read from his parents' old comic book collection, ink has flowed through his blood since he was born! And now, the self-proclaimed Comic Archivist (at least on Youtube) brings his talents for comic book history and obscurity to WhatCulture! Be warned: he's a Cyclops fanboy and a Nightwing groupie!