I suspect a lot of this has to do with recent increases of concern around sexual assault, etc. and the back-of-everyone's-head realization that a first-level charm person spell would almost certainly be used in real life by the unscrupulous as a sort of super-powered date-rape drug, not to mention coercing people into marriage and the like. (Though given that magic isn't tied to upper-body strength, it would actually be something of an equalizer between the sexes even as it increased power differentials between spellcasters and nonspellcasters.) People in the real world attempt to manipulate, slander, and even murder romantic rivals, and love potions and charms have been a staple of folklore in many cultures; you don't think people would take unfair advantage of a magic spell that actually worked?
Very few people want to drag those themes into their game. But I think everyone's a lot more aware now that a morally ambiguous enchanter who doesn't think twice about charming shopkeepers into a big discount or kobolds into killing their brethren is quite likely going to use charm person (not to mention modify memory and dominate person!) to enhance their romantic life in very unethical ways. And that's why it's now the 'evil' school. Before, if you read old Dragon mags, it was sometimes thought of as a 'pacifist' alternative to killing the goblins you found in your dungeon.