Just as nature is not evil, neither is death inherently evil.
Yet that's how humans conceive death, and not nature.

Scourge
Blood Rite
Dark Seal
Shadowfall
Shadowsear
Contagion
=Death


=Evil

=Black Mage and not White Mage

It's funny that now you have to resort to lore, but the facts are in your face. Those spells belong to BLM, not WHM. Whatever Op'rah THM's revere doesn't matter when they have abilities and spells that can be directly linked to death, and thus evil as people tend to do. Same goes for "Black".