You're absolutely right about the costumes. It's one of the reasons I have an issue with the whole trick or treat thing. The watering down of something serious and important into flimsy plastic costumes and candy.

If interested, you might want to read up on the Mari Llwd - thoroughly pagan, intended to terrify, and also intended to remind the power-holders that the great unwashed also held power over them and the means of production. Even if that power was confined to just one day a year. Christianity turned the Mari Llwd into hobby horses and rocking horses, yet the folksong Widdicombe Fair still reminds us of some of it's original power and might.