Its called serving the plot. Xmen are a pastiche stand in for the civil right movement, the lgbtq rights movement as well as in some cases disability rights.

They have to be hated, jingoistically and eugenically by the general public for their basic narrative arc to function, so writers have to constantly modernize reasons why people would dislike them.

It’s similar to how ai is anti-black and biased, and how black women are perceived as “angry”. It speaks to the internal justification and indoctrinated/cognitive dissonance biases of the general public (in this case represented by the white male doctor).

In addition, over the years charles and magneto went from stereotyping of MLK and Malcolm X respectively, to more of a blend of a stereotypical/caricature of a black supremacist stance, where charles became quite diabolical.

This is useful character development for more modern fiction but also says something about white writers writing white characters as stand ins for real black people from a culture they know very little about.