for tongue there is sweetness
for nose there are nice fragrance
for ears, there are wonderful sounds (music)
for skin, there are comfortable touches
like that, for eyes there is beauty
stimuli can be of two types
1- those giving pleasure, happiness, comfort or good state of mind
2- those giving sadness,disgust,trouble, or bad state of mind
if something or some one stimulates us in a way that brings good state of mind, we call it admirable, attractive,charming, approved, fair, favorable, popular, nice,lovely,etc
so beauty is a stimulus, that gives comfort or happiness
that's why people (we) like it , ie, popular