THey are worried that Necromancer is basically just Warlock except they use Necromantic magic instead of Fel magic, and the fact that "why do we want necromancers? we already have Death Knights"
I really would want a necromancer class since Necromancer is what is to death knight as what a Priest is to Paladins.
If blizzard can somehow integrate Paladins and Priest fine then they will have an opportunity to include necromancers.
Maybe in the 2nd lich expansion when the current lich king figured out that Necromancers are more powerful than Death Knights.
I mean I mean I hope to Arceus that If they do that I hope they make a new class/hero class. Since it would be a missed opportunity.