I find Marc Mayer's arguments fallacious. He's presenting some fallacious fallacies.
Let's consider each fallacy he mentions.
1. Art does not have to be beautiful.
What nonsense! Beauty is in the mind of the beholder. Who would buy a work of art that he/she considers to be ugly? Who would want to gaze at any piece of art on their wall if they considered it to be meaningless, or ugly, or despicable or simply trash?
However, if Mark Mayer were to make the point that art does not have to conform to a conventional, average, or normal conception of beauty, then I would agree. What might not initially appear to be beautiful must later be considered by some people to be beautiful for the art work to be of any value.
2. Art does not require skill.
Another nonsense. All human activity requires some degree of skill. Even if an artist is throwing paint at the canvas, instead of meticulously using a brush, the process and the effects of throwing paint requires a lot of practice and examination of the results. Probably most results are rejected by the artist because they are simply not beautiful, according to his taste.
3. Art does not have to have a subject or be about something.
Again, a fallacious fallacy. If the art work is about pure sensation and emotional experience, then the subject is the viewer himself.
4. Art is not a matter of taste.
Another nonsense. Everything is a matter of taste, using taste in the broad sense of sensory perception and the appreciation of that sensory perception.
If a person thinks Van Gogh paintings are crap, then that person simply has a different taste to someone who thinks Van Gogh paintings are deeply meaningful and emotionally moving.
5. Art is not a luxury.
Of course art is a luxury. Art does not provide the essentials of a secure and healthy life, such as food, shelter, clothing, transport, and so on.