I really wouldn't go or send any kids to a dojo with guys that took to dressing up a ninjas and let the kids wear what ever they want
If you have to rely on dressing up to make practice fun it really is time to look at your teaching technique
Then you would be or are a knowledgeable parent who knows something about martial arts training.
The majority of parents (moms) who bring their children (or just drop them off at the door) to martial arts classes are not very knowledgeable if at all.
They enroll their kids in martial arts classes:
1. As a form of babysitting.
2. A panacea for their kids' problems.
3. Because their kids think it would be fun.
Of course there are always exceptions but they are few.