Yes, many of us wore bows in our hair as children, and girls still do, but not these giant ones.
As a teacher I'd be worried about the children having their view blocked. We make sure each child can see, placing smaller at the front and taller behind them when necessary. If a girl wears what amounts to a hat in class, what should a teacher do? Her eyes will be at the same level but her total height is increased! 
Seems to me it's like wearing a hat in the theatre or cinema, and we know how annoying that can be for others!
Out of school - they look fun and my GD loves them. 