Teachers often don't use music in their classes for these reasons:
1. Comfort zone
We often teach what we know. It's easier to teach the songs we know than to try and learn new ones which are now available, with dynamic messages that relate to a child's life.
"I've always done it this way," is always a barrier -- not wanting to try anything new or different.
2. "Can't Sing" syndrome
If you haven't had professional training, we often say "I can't sing." Someone may have made a derogatory remark about your singing sometime in your life and you decided, "I can't sing." You may not be able to sing as well as someone else you know and so you claim, "I can't sing." SO -- you never include singing in what you're trying to do. The bottom line with music for boys and girls is: just have FUN with it! Be creative! Enjoy!
3. Collector skills need to be improved
Constantly be looking for new music and file it.