But the public reaction was outstandingly ecstatic, as comic-book fans trembled with excitement at the mere possibility of the X-Men standing in formation with the Avengers. But bringing the X-Men into the MCU would be the worst decision Disney could make, creatively speaking. But here’s the real issue - the X-Men are not superheroes, they are mutants, and it’s a deceptively important distinction. While the vast majority of Marvel’s heroes are ordinary folk augmented through technology, magic, or happy accidents, the X-Men are simply born this way. But if the X-Men franchise does become fused into the Marvel universe, its characters will instantly lose that depth, and become indistinguishable from regular, respected superheroes.

Source: Forbes January 15, 2018 13:30 UTC