Music is a primary subject. It is one of the creative areas in which people take an interest, because they like it and see it as healthy, invigorating, worthwhile, inspiring, wonderful; not because it is a step to something else.
The arts, athletics and all creative areas attract kids and adults because they are enjoyable; they are good to do; good for life. And music provides all the mind-body coordination of sports, without the bodily danger!
While research shows that studying music can strengthen the mind in other subjects, most people want to learn music just because they love music and find it interesting, not for some other reason. So, I am willing to study math, English and history, and work at getting good grades in order to be a better and more successful musician. The musical interest is first and drives the desire to be good in other subjects, so I can get scholarships, get into a better college, better job or whatever.
Music is not in schools to help academic scores, academics are in school to help kids be better musicians and improve growth in all creative areas.