And it would logically follow that other schools of magic would be likewise suspect.
Once Necromancy is banned, someone is sure to protest the summoning of Outsiders (Conjuration, Druidic types in particular would be less-than-fond of Outsiders traipsing around the natural world), or magically spying on people (Divination, which the nobility and merchant class would *heartily* approve of, since they could get away with so much more), or the deliberate use of lies and deception (Illusion, various fans of truth, honor and justice, offended by the idea of an entire school of magic devoted to lying to people), or mind-controlling magics that turn break all laws and violate basic human dignity by enslaving people (Enchantment).
Once the sled gets going down that slope, Evocation really doesn't have many *nice* uses, does it? So dangerous. Best to forbid it's practice (and training, and even preparation of 'the magics of destruction and war') within the city limits, save in times of war, under appropriate military supervision, especially those related to *fire* after that massive and tragic and oh-so-convenient fire that sprung up in the poor quarter last fall...
By the end of it, Abjuration will likely be the only school of college that *doesn't* mortally offend people on a visceral level, but even then, a few (faked, obviously) instances of athletes or duelists or champions 'cheating' through the use of Abjuration spells could pump up a groundswell of support for banning this last school of arcane magic. One beloved champion being humiliated by some foreign champion, one of those thrice-damned Thayvians, because he cheated and used Abjuration spells to ward away the city champion's blade, and the tide will easily erode the last arcane school.
Who would have a reason to go anti-arcanist? Devotees of Shar, Bane or that sphere of annhilation thing they worship in Luthcheq / Chessenta or anyone else who has an axe to grind with Mystra and her mad power-grab. The clergy of Kelemvore don't have to be evil, just misguided. It's *perfectly reasonable* for them to want to control Necromancy, just as Talos would like to enhance his portfolio to include Wild Magic and destructive magic, and Cyruk has tried to move in on the Illusion school. Mystra's not in the strongest position, and the other gods are like wolves, circling in and trying to pick apart her portfolio to enhance their own.