Yeah, no kidding. Magneto was so good in First Class and Days of Future Past. Then Singer lost focus of the character. When he joined Apocalypse in the third film, I literally exclaimed "Oh, **** YOU!" at my television screen. It was a complete betrayal of the character, both who he was before and who was to become in later films. Magneto does not want to bring about the end of the world. It's questionable that Magneto is even interested in ruling the world. He wants mutant dominance... and not even dominance in many cases. He's most often pursuing mutant security, probably an enclave, a safe haven. He doesn't participate in the wholesale murder of other mutants because he respects all other mutants. He's trying to further the mutant cause and bring all mutants to his side, not kill those who disagree. It's what makes the Xavier/Magneto relationship so great. And the notion that he'd participate in a world-ending event, essentially genocide, out of which he was borne, is ludicrous. Magneto is an enduring, interesting character because he's not a paper-thin villain. He's not a bad guy. He's a complex, rich character with very specific goals. Sometimes those goals are noble. In many cases, maybe even most cases, they are noble goals. It's the means he uses to achieve those goals that are villainous.