...agreed. While it's nice to be able to put every kid on the instrument of their dreams....

1. They might not be suited for that instrument,

and,

2. The director has to have the best interests of the band as a whole in mind. 30 percussionists, 3 clarinets, and a trumpet aren't a band...that's 30 percussionists, 3 clarinets, and a trumpet.