Wizard, cleric, druid, witch, and shaman all have similar spellcasting mechanics. They have the fastest spell progression (i.e., access to a new spell level at each odd-numbered class level), which means they are the first to get 9th level spells. They are also all prepared casters, meaning that they have the widest spell selection. As a result, they are often considered the most powerful spellcasting classes. Some of them may use Charisma for class features, but their primary casting abilities are either Intelligence or Wisdom.
Where, if at all, has Paizo (or its designers) ever explained why there are no similar spellcasters that use Charisma as their primary casting ability? Is this an intentional choice meant to balance the mechanical advantages between classes? Or have they suggested any plans to implement such a class in future content?