A brief response to the following point in this comment on this blog:
"Artists in the Dada movement purposely countered the established traditions of aesthetically pleasing art because of its irrelevance and bourgeois classicist association. It was the art of the rich who were sheltered from the horrors of war"
Consider a graph such as this one: ("Damien Hirst's Spot Prices"), and tell me that modern/contemporary art still represents the common man today, and not the rich. Also, thanks to numerous economic and technological advances, beautiful art IS now within the reach of even lower economic classes. The historical situation has changed - in some senses, reversed.
Related: How Contemporary Art Lost Its Glamour:
"Suddenly, the press dares to criticise contemporary art. A number of coinciding events seem to have focussed a new, less reverential attitude towards the spin of the art world ... Hirst's auction took £70.5 million on the day that Lehman Brothers went bust. A lot has been made of this coincidence — certainly it emphasised the irrationality and the untouchability of the art world"