Job Alignment Chart

[Ashkendor]

Main reasoning for evil:
“In days long past, there existed an evil clan and arcane art known as black magic—a potent magic of pure destructive force born forth by a sorceress of unparalleled power. Those who learned to wield this instrument of ruin came to be called black mages, out of both fear and respect for their gift. Yet great power served to corrupt the judgment of mortal man, and so he unknowingly set out upon the path of ruin.
Adventurers who take the black will become agents of devastation, capable of annihilating those who oppose them through little more than the force of their will.”
—Game Description

The War of the Magi is hundreds of years in the past. Modern adventurers have nothing to do with that "evil clan" from ancient times.

I mean, on one hand you say SMN are "summoning demons" but since they do it for the good of the party it makes them Neutral instead of Evil. Black Mages are channeling the power of the void for the good of the party. Why is that any different?

Play the DRK quests if you havent already... all I will say

I have. Lawful Evil is completely wrong for DRK. They protect the weak and innocent.