Felon, two things:
1. Power source. There's a power source tailor made for the necromancer -- and arcane/divine ain't it.
It is quite peculiar to hear someone say that, as the weight of D&D's history contradicts it. Arcane has always been the power source for necromancers--a wizard specialization--for all the previous editions. People's minds didn't seem to reject it for all of those decades. Moreover, in the current system the groundwork is already partially laid, as there are plenty of necromancy-themed spells in the wizard's arsenal. So clearly, the arcane power source is capable of channeling those dark forces.
The whole idea of making an entire class just to attach it to a more-fitting power source seems to be rather capricious. There's a lot of work to do to distinguish a class after attaching a spiffy new power source. Consider the monk, which was originally slated for the ki power source. The designers looked it over and wisely decided that power source wasn't sufficiently justified just because it "felt" more correct.
2. Features. The necromancer should be a pet class with summons, and at the moment, there are two pet classes (ok, one pet class, one pet build for an existing class) and neither have summons, or really, should. One could add an always-on pet build for wizards, which would probably be closest -- but should a necromancer really be an Int-primary class? Maybe...but I'd argue for Charisma, really.
The litmus test for making a new class or just attaching a build to a new one isn't purely arbitrary. Look at the assets that a wizard has and see how they sync up to the necromancer. For example, is it vital that necromancers have access to an implement that wizards don't? How essential is it that a necromancer use another ability score besides Int? Does the concept demand more than cloth armor? Are the appropriate types of damage represented (e.g. necrotic, cold, etc)? Taking away and adding class features is a pretty well-accepted practice, so that alone isn't a deal-breaker. And other than that, I'd say we have a lot of checked boxes under the wizard, so a new class is for the most part a big, fat copy-paste.
As to the whole "pet class" notion, being able to toss a daily spell that summons minons and keeps them around for the rest of the fight could do the trick. If you want to dig beyond the dailies, you can tap into utilities for additional summons, as was done in Arcane Power. It's not what some people yearn for--which is to have minions permanently on-tap--but that yearning is really just hearkening the status of the necromancer as iconic arch-villain.
Of course it's hard to give up on the idea of a necromancer with thralls at all times, because as an arch-villain, he has mooks at his disposal. As a player character, he's part of a party, not a party unto himself. Gotta make adjustments for that.
Now, a ranger has a real perma-pet, and I have long thought would work for another striker who's already desperately in need of a damage boost--the warlock. Each of the extant warlock pacts seem to lend themselves easily to a subset of pets, and the other fundamentals (implements, available damage types, and so forth) also fit. How about this for a necromantic pact boon: when a cursed enemy dies, the necromancer gets to summon a mook on that spot?
In short, there's plenty of fine clay to work with here.
And no I am not saying 5e is around the corner, it just it looks like it will be at least 3 years of 4e before we can see a necromancer which is long time for something that is fairly iconic.
