Among the most radical—and, some might argue, the most pernicious—is the postmodernist critique of objectivity in aesthetic judgments. This school of thought sees much art as an affirmation of European elitist attitudes driven by imperialistic and capitalistic motives. Unsurprisingly, a lot of postmodern conceptual art can only be understood (if it can be understood) as a reaction to the older and more traditional aesthetic norms.
Conservative philosopher Roger Scruton believes that postmodernism has gone too far, and that it has created a culture of fake originality where desecration and shock value for the sake of shock value have become the new norm (I highly recommend reading the article before watching the documentary below, since it provides the context necessary to properly understand where Scruton is coming from). In his opinion, beauty must regain its former centrality in art because art must play a redeeming and inspiring role.
Let this be the start of a fascinating dialogue and conceptual exploration. :)