IMHO the artist only achieves a work of art if, whatever else it may be, it is beautiful. And the greater the beauty, the better it is.
In modern times, beauty is perceived as a distraction from the artist's true pursuit, which is making a personal statement. By personal statement I mean both in terms of the way the artist paints, draws, or collages, etc., by also in terms of what the artist wants to "say."
Most modern artists are trying to create something unique. "Derivative" is a bad word.While art history is still taught, mastering someone else's technique is rarely advised, lest it delay or worse, derail an artist's personal creativity. While these artists may profess to be influenced by other artists, they do not consider themselves to be real artists until they have developed a technique or approach or subject which no other artist has ever used.
Modern artists also want to express their opinions on political and cultural events and more's through their art. These artists decry what they believe to be evil, often using little subtlety to express their anger and angst. This is hardly unknown historically, but the pervasiveness of the attitude is.
Similarly, many modern artists like to see themselves as rebellious, which attitude pours alchohol upon the flames of anger and despair.
I haven't enough education in art history to place this attitude into historical perspective, but if I had to guess, I would argue that Picasso was an early example, and that his success gave impetus to it.
What is the role of the art critic in all this? I think it is central. They are the arbiters of taste. I wonder when art critique became so central to the education of the artist, and art critics became the tastemakers.
I don't know why art critics began to prefer novelty of technique and rebellious anger and angst over beauty as a standard. Perhaps it was iterative, the artist and the critic supporting one another; but I wonder if art critics became famous with the advent of mass communication. Perhaps the creation of mass media and communication made art accessible to the many, and the many were looking for direction about what to buy. They were contemptuously told that they could not rely on their own uneducated understanding: "I don't know about art, but I know what I like!" is a statement held up to ridicule.
More later