The Necromancer is Underpowered Reason 12: Mobility

Since necromancers obviously can solo Hell even on /players8 (I've done it), my case that the necromancer is underpowered compared to the other classes rests largely on killing speed. Versatility and survivability are nice too. But there are a lot of monsters to kill. Efficiently wiping out large mobs and the bosses leading them is a hallmark of a good character and perhaps even the hallmark of a good character. A character does not necessarily need to move quickly in order to kill quickly. Simply walking around from dungeon to dungeon slaughtering everything is entirely possible, if a bit tedious. But even if it isn't a necessity, mobility is wonderful to have. Being fast makes the game more fun, makes targeted boss-runs possible, and is helpful for survivability.

Someone who actually read all of these posts, but had never played the game, would probably anticipate, incorrectly, that I would launch into an explanation of why every other class has better mobility skills than the necromancer does. But veteran Diablo II players already know what's coming. It's not that other classes have better mobility skills: the necromancer doesn't have any. The necromancer's mobility skills are not merely inferior. They are nonexistent.

Sorceress: Teleport.
Assassin: Burst of Speed, Dragon Flight.
Barbarian: Increased Stamina, Increased Speed, Leap, Leap Attack, Whirlwind, Frenzy, Battle Orders.
Paladin: Vigor, Charge.
Druid: Werewolf, Feral Rage.
Amazon: None.
Necromancer: None.

The amazon and the necromancer are the only two classes that are completely devoid of mobility skills. This list might be mildly deceptive in that the barbarian has seven mobility skills, but most of them are only minor, while the sorceress has just one, but it's the best one in the game. However, both the amazon and the necromancer are adversely affected by this, being generally less mobile than other classes. Druids that are not werewolves are similarly affected. This reason isn't as strong as the others because mobility isn't as important as killing power or survivability and because another class is in the same situation, but this is still another way in which necromancers are underpowered. Also, amazons usually either fire bows or throw javelins, so they can strike from a great distance, mitigating the problem of mobility in combat. The only necromancer build that can fight from such a distance is the bone necromancer. I've already covered the problems with bone necromancers (less damage and more skill points needed than other magic damage specialists). Other necromancers need to get close, whether it's to hit with melee weapons or to launch Poison Novas. Even summoners have to briefly close the distance to bring their skeletons to the enemy.