Without careful and authoritatively supported definitions of the terms "average person" or "common man" and "elitists" your argument spirals in the direction of Nazi-era appeals to populism and the dogma of "degenerate art." You need to separate your weakly supported contrast between what you call elitism from fascist and proto-fascist appeals to populism (undefined claims of value about the wisdom of the common man). One way you can do this is by constructing a counter-argument on the basis of a scholarly article such as the one linked below:

http://www.jamescockroft.com/postmodern-art-and-architecture-in-the-third-reich/

You need to either concede or refute the historical association of notions of "art decline" with the Third Reich's concept of "degenerate art" and most importantly, you need to make very clear that what you have in mind correlates to your concluding paragraph which appeals to the principle of democratic access to visual art, which is different idea altogether from polemics about rise and decline of a particular art form on the basis of its audience appeal.