Human history is littered with examples of ideas that were thought beautiful in their time, and continued to have a following long after their inherent ugliness—and evil—was revealed.
Beauty is not a thing; it is an experience. Beauty is when the mind says, “There is symmetry here and I must find it!” Ugliness is when the mind takes one look and gives up.
The Kabbalah calls the world we live in the World of Falsehood. Why? Because in this world our five senses experience only the outer veneer of a deeper reality.
To the Jewish Mind, if something can be perceived as holy, then it is by definition both beautiful and true. And if cannot be perceived as holy, than it can neither be beautiful, nor true.