Tokens

Hey, pretty new player here, and I wanted to ask a question about tokens.

Why are they grouped like they are at the moment?
For example: Paladin, Priester and Warlock as Conqueror; or Warrior, Shaman, Monk and Hunter as Protector; or Vanquisher for Rogue, Druid, Death Knight and Mage?

Priest does not have a feeling of a Conqueror for me.