This has been bugging me ever since my first play through of the Mages Guild quest-line. From what I have gathered through npc conversations, Necromancy used to be as respected throughout the Mages Guild as any of the other main magic types. Destruction, Illusion ect. Traven bans necromancy from the guild but it's still technically legal. You never meet any necromancers in the city, except for Hassildor's aide, and the only reason I can see for this is that being banned from the guild has unleashed all ignorant local superstition like a wave, added on top of that the pressure from the local guild halls must of made life for these perfectly normal citizens unbearable, sending them into an exodus from polite society into caves to study their craft. I think that kind of banishment is enough to drive anyone insane. Now I'm sure that they started out making regular pleas at the University, peaceful protests, letters of petition. And when all that failed, they did what any ignored minority would do when sufficiently oppressed, they turned to extremism, latching themselves onto a fringe organization led by the Necromancer equivalent of Osama Bin Laden. This group of necromancers is essentially The Black Panther organization, except instead of racial prejudice, it's some kind of religious/vocational apartheid.
Traven then forces you to slaughter dozens of civilians to get at Mannimarco, instead of appealing to the more sensible of them and offering them concessions, he has you butcher these ordinarily rational people who have been driven to extremism by horrific circumstances.
And thus I rest my case that Traven is a jerk who deserved to have his soul svcked into a rock.