Would you like to play as a Necromancer?

Necromancers are inherently evil. I don't understand something; the knight at least had some people left alive, but the necromancer waited until they were all killed? He acts only for his own benefit; he has neither fighting spirit nor a feeling that allows him to sometimes do things not as "right," but as his heart dictates. Your example is quite stereotypical; why did you decide that the knight would act exactly this way and not otherwise? You don't take into account the human factor, which gives people strength, the feeling that makes them protect others, sacrificing themselves.
P.S. "fan" is a strong word; I just like playing as them, but in real life, I would prefer to be a knight in golden armor, doing good, rather than destroying everything.
And one more thing... I liked the information because of Agrail, who, although transformed, still had his own will and did not want to harm Isabelle.