Language is primarily conceived of as a vehicle of thought and a tool for human communication. Secondarily, however, language is also an aesthetic object, admired for its use in poetry and in accompaniment of song. Poetic devices like alliteration and rhyme are to be found as well in ordinary speech as an enhancement of communicative role. These are all instances of language use involving aesthetics as well as the referential function.
One further aesthetic aspect of language use is authenticity. This was illustrated to Y-H-B yesterday on a flight between NY/JFK and LAX, when I heard the pilot making an announcement to the passengers aboard. He spoke in a perfect Boston accent, of the sort I used to hear all around me when I lived in Cambridge, Mass. As a graduate student and research fellow. The aesthetic appeal of hearing an authentic Boston accent, with all its deviations from Standard American English, was what captured my attention, not the content of the announcement. I silently congratulated the pilot for adhering to the variety of speech that he had grown up with.