I think generally art is a good class to have: it's important for children, in my opinion, to be taught a variety of things they can learn to do to find what they enjoy. However, I'm not sure how long it should be a required class- perhaps making it an optional class for upper levels remains a better option? For starters, forcing children to use specific creative outlets whether they enjoy it or not, at a certain point, can be more harmful than good, I think. Plus, required classes tend to be graded in a way that focuses on 'skill level', and that can be bad for self esteem, and on some level, makes it less like a 'creative outlet' as it should be in my opinion...
However, I think adding art to already existing classes would also help students quite a bit! In one of my special needs high schools, most of our teachers did double duty- for example, my history teacher also taught music, and my math teacher taught art. For one of our major things in math, our teacher actually included an art project: it was basically instead of one of our smaller exams. She had us make posters that showed how we used math in a way that was important to us (for example, mine was about averaging word counts for NaNoWriMo). She was also one of the few remaining teachers I had that didn't mind me doodling in class or drawing on the back of my test afterwards (in fact, she encouraged it and sometimes gave us something math-related to draw, like fractals). Art has many uses- it can make subjects we normally hate or struggle with more bearable, if it's in a form you enjoy. So rather than a dedicated art class, I think at some points, making art just a general addition to regular classes might be more helpful in a way...