Why are there so few Clerics and Shamans?

[Edward McGee]

Clerics and Shamans share many of the same benefits.

They can wear medium armor.
They are full casters based on wisdom. A good stat to have high.
They can both channel to heal. Shaman has to take Life Spirit as a primary or wandering spirit or be a Witch Doctor to do so.
They both have Diplomacy as a class skill and a reason to boost charisma.
And they both have useful abilities when not casting spells. Domain abilities for the cleric and Hexes for the shaman.

But I rarely see either class locally.

Do people just see them as second rate Life Oracles?

What are your thoughts on these classes?