Why are there so few Clerics and Shamans?

[TimD]

Character decisions are generally made by role fulfillment at this point, rather than class. While Clerics can manage several different roles to some degree they are no longer the top of any given role that they once were before the advent of life oracles.
That said, I have several clerics that I play off and on, especially my "Purpose-built 1st", Kermitous. It may just be an anomoly.

Shamans start late so may not be as attractive as many of the other newer classes and their abilities are a bit less intuitiive than most.