This is a very good question. It is important to keep in mind that there will not be one right answer but only opinions. With that stated, here are my thoughts on the role of art in society. First, on the most basic level, art seeks to please people with beauty. In a broken world, sometimes it is important to allow people to realize that there is still beauty. Hence, art can function to refresh people and remind people of better things or transcendent realities.
Second, on a more deeper level, art is able to express important values within that society to people in ways that are memorable. In this way, art can be used to reinforce values and even bring people together. For instance, artwork can commemorate great accomplishments, such as military victory as in World War II.
Third, art in society can also be used to challenge people. For example, a thought provoking piece of art can call into question the establishment or some other cherished ideal. This would be a more subversive use of art. In the end, art has many different functions in society.