Arabic scales known as Maqams and the gamalen's colotomic structure produce very symmetrical scales and rhythms. Two very beautiful musical traditions.
It becomes very obvious that every scale you can play also has a rhythm associated with it when you look at it constructed on a circle with the unison and the octave at the top in the same location. It’s manifestly apparent that some of the Arabic scales have notes which are half-flat or quarter tones for reasons of visual symmetry. It seemed to me unusual that the starting note for many maqams was not the one on the axis of symmetry.
The form of a piece of music is another place where we often find a little symmetry. Beethoven and others were of the opinion that if you are writing a long piece then the beginning goes nowhere fast so you are alerted to the fact it's going to be a longer composition and likewise the ending needed to match the beginning in size somewhat and also relate to the scope of the entire piece.
Jazz tunes play the head, improvise and then return to the head. If the head is short, they play the head twice and the ending twice. This is a kind of symmetry without going to the extent of playing the theme backwards at the end which we don't expect in our tradition.
Symmetry is actually rare in nature except in the faces and bodies of animals. Trees, lakes, rivers, mountains etc. are not symmetrical. Music which does not have the symmetrical elements previously presented has the aesthetic of the nomad not seeing many faces or symmetrical buildings who often lives alone closer to nature and derives his aesthetic from that.
Perhaps a reason to use self retrograding rhythmic structures similar to palinromes in literature such as "A man, a plan, a canal. Panama." is not because of a need for symmetry. It's because the retrograde implies a desire to go backwad in time perhaps to a golden age. This is a little regressive however.
Then there are philosophical considerations. In the Heterotopia where we actually live, we have to honor the interests and aptitudes of the composer, the performer and the audience. We cannot mirror a utopia in which we do not believe.
One based on elitism, ageism, classism, sexism and all. In my case, I'm a composer whose interests and aptitudes cluster around symbols. As such, when made aware of the fact the very notes themselves have symbollic meaning, these symbols are of interest to me.