Why do contemporary artworks make particular demands on audience?

Answer 1

In what way does contemporary artwork make demands on its audience?

Answer 2

Well, particular demands...
Contemporary Art is as specialized a field of work as any you might think of.
When producing a work, not only you are interacting with the world you live in (And that's already a tall order, the world being so intricate and complex) but you are relating with the history of culture and your medium.
These are specialized skills.
Art, like Physics or any other area, depends on the establishment of codes and languages which allow meaningful communication and understanding. Just like in Physics you need to possess a modicum of basic scientific language and concepts to even enter the ball game, so is with Art.
The problem is not so much with Art itself but in our culture's specialization of labor:
We are encouraged to become experts in a file, but the masses of information required to become one leave very little time for anything else. You might be a really good computer engineer but in order to become one you had to leave lots of things behind.
Because Art plays such a small role in our contemporary lives, it is one of the first things to go.
All fields of human endeavor have been evolving for millenia, so has Art.
It's becoming more and more complicated for anybody outside a specific field to actually have a grasp on the latest developments of any but the one we became professionals of.
It's not Art that makes particular demands.
Everything does,
It's just that, like everything else, it's changing and developing too fast for most of us to keep up.