No. That is not the argument.
Your argument is that "necromancers are ranged death knights".
And the problem with that statement of yours is that you ignore current examples within the game that contradict this posture. Case in point: priests, in the majority of RPG games, tend to be the "holy/pious character". If it was added into WoW the way it is often depicted, it'd be a "holy/holy/holy" class, just like the paladin is "holy/holy/holy".
Which, mind you, would be
completely fine, in my opinion, because I can think of a healing spec based on heavy heals, a healing spec based on light heals but mostly shields, and a DPS spec possibly called "
Inquisition".
But perhaps Blizzard thought that two classes having the exact same magic-school-based specs was not enough, and decided to give the priest class the "Shadow" spec to further differentiate it from the paladin class. But on the other hand, though, they could have instead made the DPS spec of the paladin a shadow spec, since Paladins are supposed to be defenders, and "revenge" is usually frowned up, which is basically what "retribution" is.
The point of us pointing out at the priest/paladin situation, Teriz, is exactly because of that: Blizzard can give something new to the necromancer class that the death knights don't have access to, if that truly is an issue.
And there is enough lore to support that.