I think blame for X-Men Apocalypse has to be shared by Bryan Singer and indifferent/malignant Fox executives (like Tom Rothman) tainting the franchise right from the start. When the first X-Men movie came out nobody in Hollywood took comic book adaptations seriously. Only the "super nerds" would care if they fucked up these characters or left out some of the more 'cosmic' elements of the original stories. While I had a lot of problems with that first X-Men film, I saw a lot of promise going forward as well. Wolverine was great. Patrick Stewart was perfect as Professor X. It seemed like a good start that could only get better as it went on. But the lazy creative decisions made in that first movie grew over time and spread like a disease, infecting the later sequels (and prequels).

While Ratner got the brunt of the blame for 'ruining' Last Stand that film was a culmination of plotlines and creative decisions started by Bryan Singer in the first two X-movies. Singer's complete mishandling of the character Rogue in the first movie, the boring woodenness of every X-Man besides Wolverine and the flippant attitude to introducing and killing off classic characters (without getting into their backstories, or as in the case of Lady Deathstrike, even allowing them to speak) belies a lack of knowledge, affection, or interest in the original comic books or its characters.

X-Men: First Class was set in the past, just to get further distance from the awfulness of that trilogy of movies, but for some reason Singer somehow was permitted to return for Days of Future's Past (working from a script developed by Matthew Vaughn and Jane Goldman). Like adamantium bones, Bryan Singer's been slowly poisoning this franchise from the inside this whole time. Only now with Apocalypse (after having two pretty good X-movies in a row to compare his work to) has his shortcomings as a director and storyteller become glaringly obvious to everyone.