Art changes, it swirls, but it reflects its time. It even peers into the future a bit.
"Art changes", well, yes and no. The ways and means of "art" in history have evolved with the tastes of the patron. To take the polish off it up until the late 19th century artists were essentially "caftsmen" who, subject to the open market, created those objects d'arte that would appeal to the potential buys. Far and away those patrons were aristrocrats and/ or those aspiring to patina of aristrostcracy.
Then came the Industrial Revolution complete with the upper class scorn of "crass millonaires". Snobbery, in the worse sense of the word, came into being; b/c there was no way the aristo. could compete with the indstrialist when it came to money and posession.
The snooty attitude of "ar-teests" is merely a spin off of this contempt: You know, "Well, anybody who is anybody knows that this is a work of art. You DO agree don't you?"