So, I think I know why I don't like the Necromancer.
It's not that they're a bad class. It's that the class forces you into one type of gameplay to be effective: The Condition Master. Swapping, sapping, and tossing conditions is a cool concept, but not everybody wants to play that type of character. Unfortunately, minions are weak, and life-drain spec doesn't come online until about level 30 (and then you're still only really OK at solo PvE).
Pumping my Power stat and killing things by draining their life force and adding it to my own should be a legitimate playstyle. Raising armies of undead to fight for me so that I don't have to get my hands dirty should be a legitimate playstyle.
But every weapon combination forces some sort of long-cooldown aoe condition-inducing effects on your build. No matter what weapon choices you make, you'll always end up sacrificing pure damage for a crappy bleed or a short-duration poison. There are no weapon choices that allow you to create minions from the enemies you kill. There's only a single life-drain weapon skill on any weapon, and it's a single-target channeled ability on the dagger with a 600 range, for christ sake.
I'm not saying that you can't build a necromancer however you want and still get some sort of enjoyment out of it. I'm simply saying that there's one clear "best" build for this class, and I don't want to feel like I'm intentionally gimping myself, just so I can be my own special snowflake.