It might also have to do with positive connotations in the word, “brilliant.” Smart or intelligent doesn’t have those connotations. “brilliant,” after all, refers to light.
I don't see it. There are beautiful people who are also not great humanitarians - Che Guevara was a mass murderer, but is an icon, because he was good-looking. Einstein was brilliant. He was also borderline communist. The Rosenbergs were brilliant scientists. But they also handed over to the Soviets the recipe for the atomic bomb.