who decides what and why?

According to Wikipedia.com, Marxist aesthetics "involves a dialectical approach to the application of Marxism to the cultural sphere, specifically areas related to taste such as art, beauty, etc. Marxists believe that economic and social conditions affect every aspect of an individual's life, from religious beliefs to legal systems to cultural frameworks. The role of art is not only to represent such conditions truthfully, but also to seek to improve them."

Such is the belief of Richard Ohmann, who, in his essay entitled "The Shaping of a Canon: U.S. Fiction, 1960-1975," discusses the impact of what he calls the "professional-managerial" class upon the American literary canon. Essentially, Ohmann argues that the best-selling fiction works are published, reviewed, and advertised by the professional-managerial class. He writes that

a small group of book buyers formed a screen through which novels passed on
their way to commercial success; a handful of agents and editors picked the
novels that would compete for the notice of those buyers; and a tight network of
advertisers and reviewers, organized around the New York Times Book
Review, selected from these a few to be recognized as compelling,
important, 'talked-about' (Ohmann, 1884).

What all this means is that there could possibly be hundreds of great works of fiction written every year--and the public wouldn't know a thing about them, because the group of people that publish books benefit the group that advertises them benefit the group that reviews them benefit the group that publish them. Wait...what??

I'm not entirely sure what I think about all this "Excellence based on socially chosen values which are constantly changing" discourse. It makes sense in a way...in monetary and financial terms, businesses try to work symbiotically (especially when they all work in the same area, such as novels). And when these businesses work together so tightly, they're bound to be comprised of employees (people! we're still people that breathe and have the capacity to think individually) that have similar values and ideologies. So yes, the works published/advertised/reviewed by these symbiotic businesses and pushed to the top of the best-seller list most likely will contain those same types of values and ideologies. Does this mean that a work published outside of the symbiosis will never succeed? Ohmann might say yes. I'm gonna say no. Call me an optimist, but I think that if a book is truly artistic and meaningful, then it will push its way to the top at some point or another. Maybe not while the author is living, like most of the books that make it to the top of the list, perhaps it will surface later on (see Emily Dickinson).