Also, False Profit, my life experience tells me that even those lacking in technical, intellectual abilities can be imbued with a kind of intuitive sense that guides them through life in a constructive, creative manner, and that this is actually not even that rare.
It is amply obvious that this sort of being, beyond not being inherently destructive or parasitic, could actually fulfill a constructive, transcendant role within a properly organized social order.
I think perhaps people are thinking of manipulating somewhat of a dichotomy which can be used to mark the levels of a caste system in which they wish to purge the lowest who in a well designed society may not be needed. The error, though, seems to be the assumption that each caste was traditionally filled by one sort of person. In reality castes seem to be what could be called subcultures or a micro society. This seems to be somewhat true historically if you look at the highest caste in the Celtic system (which I have heard is nearly identical to that of Ancient India) where what we could call the priestly caste is made up of 3 subcastes who explore this niche in different ways. There are the bards, the vates, and the druids. All have different duties tailored to their qualities and characteristics I presume. The bards would be those with artistic talent (able to express ideas in a more accessible way). The vates, I believe are supposed to have been well versed in what we could call seership and would have been responsible for the application of ritual (preservers of culture). The druids, from the little we know of them, seem to have held both the philosophical and judicial duties of society (essentially thinkers and designers). These three different roles and niches, obviously require very different talents, personalities, skills, and intelligences. An artist for instance, may be a good communicator, able to express well. A seer may be very intuitive, be drawn to the esoteric, and have a full grasp not only of the purpose of ritual but how to implement it into society. The life of a druid, would require a person wary of their own bias, perceptive towards the closest possible aproximation of reality, and a mind which recognizes systems along with all of their parts and mechanisms.
As far as using IQ as a guide to who would belong in the highest strata of society, in this case a priestly caste, the druids would most likely score the highest. With that intelligence, though, even they would realize that the vates and bards are also needed to address the holistic needs, stresses, and conflicts found within any stratified society.