as a child i did not play an instrument, and music class had minimal impact on me. art class was very enjoyable, but not a subject i would necessarily leave in the curriculum if something had to go.
but seeing how art is woven into the schools my children now attend has opened my eyes to its potential. it's used more as a vehicle, particularly at my kid's elementary program. art and music are a part of the school culture, the glue that holds the student body, staff and parents together. art is used to introduce concepts, build on and solidify learning and often as a means to express the culmination of a body of knowledge.
in this sense art brings the learning to life at the elementary level.
at the secondary level, it seems more specialized and appears to be the "raison d'etre for some students to continue their education --- SOTA, or at least continues to be a vehicle for delving into the core subjects.
and come to think of it, at the preschool level, art is the primary subject, period. why it becomes dispensable after that is puzzling.
pam