There has been much written on intelligence of different types recently. And your view that it is rare is true. Persons like Buddha agreed with you. In this way our lack of intelligence can be overcome by learning. So for example, the person dominated by anger can easily learn to remove most of the anger if she is motivated to do so.
Anger is the emotional symptom of lack of intelligence about the true nature of life.
Removing it greatly increases the person's intelligence. That being said, however, I don't want to say that a Buddhist is automatically moral-smarter. But I do think that if you measured it in a group of Buddhists, their scores would average much higher than the general population. I am remembering a conversation I had with a black parole officer a few years ago. He thought it important to come up with an educational curriculum to help kids stay out of trouble.