My understanding from Shadowbringers is that Darkness represents exuberance and mutation while Light represents stillness and stagnation. They stated that this the reason why Voidsent and other creatures of darkness look "grotesque" while creatures of light like the Sin Eaters look more "divine" or "majestic". (Although, there were definitely some FUGLY Sin Eaters like Tesleen and some hot Voidsent like Cloud of Darkness.)

But yes, psychologically, Hydaelyn being easier on the eyes definitely contributes to people stanning her no matter what.