There is complexity because the artist, the writer, doesn’t know why he or she is doing the work. That complexity results from a lack of clarity.
There is complexity because the creator of the work wants to confuse. This is common in academia. The author includes as much extraneous detail as possible in order to impress the reader with his knowledge. The painter paints detail because she wants to impress people with her skill. In fact, it is more difficult to be simple and clear than to be obscure.
Finally, there is complexity because life is complex.
The artist’s role is to find the transcendent truth that lies under the complexity, and paint or write that.