I have heard that when it comes to faces, symmetry is attractive and beautiful. But, too symmetrical runs into the uncanny valley problem that digital faces used to have (before AI created them with flaws). But I think the symmetry is also in the reflection of the familiar, which is why societal environments can prime us for what is beautiful to us. If it doesn't challenge us too much we can like it. But, if we are challenged, we can see it as ugly, until we see it enough that it is now familiar - and then the cycle repeats.