In my opinion, Music and arts should and needn't be compulsory subjects at school prefer to the students.

Firstly, they will help students to enjoy for some moment, because this lessons are not difficult, which won't need to use all their brain. 

Secondly, Art and music are very creative and vast subjects. However they are not necessary that everyone shall be a good musician or good at art. Hence music and art as compulsory subjects sound to be wrong.
It is nice if schools have infrastructure facilities to teach art and music. Those who have a deep aptitude for art and music can take-up those subjects and even master those for that matter.Aside from being supportive, I think learning the art and music subjects can be time consuming for students. Devoting time to main subjects is a paramount importance for success in the examinations and future career. Hence and art and music may be optional but not compulsory.

I don't think music and arts are compulsory subjects for the following reasons:

Firstly, music and art are gifted and not compulsory, but they are still subjects in the first and second degree programs.Secondly, music and art are subjects to entertain and nurture artistic talent. Finally, music and art are the subjects of study while the main subjects are subjects such as mathematics, physics, English, chemistry, biology.
But in my view, we should still consider music and art as subjects and we still need to learn, not without learning.