1) Either the masses don't understand modern art:
As a result, many artists decided that they would deliberately make their art too "difficult," too strange, for the masses to understand. In a movement known as modernism, artists decided to exclude the masses from art.
2) Or they do understand it and just don't appreciate it:
Most people do not disagree with modern art because of its methods or media. They disagree with it because of its aims and purposes; they disagree with its worldview.
And how can you coherently speak of the "world view of modern art" as if that were one clearly identifiable thing? I can point to so called modernist and postmodernist artists who had very different world views and ideologies. Some of them, like T.S. Elliot, were professing Christians.
And, lastly, how is being inaccessible to the masses per se a spiritual problem? Quantum Physics is inaccessible to the masses.
Great! He's an art critic now ... so versatile ...