Lich should allow one to influence undead.

It does...

No, Necromancers get that ability when they specialize. People who get Lich from the Crypt don't have it.

Can't say this would be bad, honestly.

Just curious, but what's the story rationale behind needing Necromancy or Crow's favor to influence undead?

I remember wondering this way back when (sans the Crow thing). Aside from mindless undead (which you'd think couldn't be influenced at all), thinking and coherent undead would be just as susceptible to conversational gambits as the living.

Or did they just not come up with any other influence-related skills that could be used instead?

Doesn't it already? I was able to influence Ladantine as a lich.

You can influence the undead as a lich. I couldn't influence priestesses in Shallamurine until I liched.

you can influence undead leaders regardless of life/undeath, such as ladantine and the guy in paavik, i believe

Most undead have a hard time keeping track of mortals. Example: you can't see room entrance/exit messages while dead. Necromancers/Crow know how to keep their attention. Liches are not effected as they are much better attached to their body than your standard Angkrag miner.