When I was little we weren't allowed to do anything for Halloween but now that I have a 6yr old I let him dress up in a non-scary costume & take him trick or treating. It's nice to let your kids have a little fun besides they dont see culture or religion.
Its a chance to have fun, dress up and get out for both children and adults. Kids go trick or treating for candy, the tradition is very old. It started hundreds of years ago to disguise yourself as a spirt and go out on all hallows day asking for money or food, it used to be given in exchange for prayers for the dead. Mexico celebrates it on Nov 2nd this year, its called Dia de la Muerta and celebrates the dead. They usually have a party or gathering, remember family & friends who have died and eat cakes, candies and specifically ones called sugar skulls that are really pretty. Lots of cultures celebrate it, now days for adults its a fun time to dress up, go out and have fun.
I'm curious too. Its not a big deal where I am but is growing in popularity. We were never allowed to go trick or treating when I was a kid and no one I knew did either because it was seen as not part of our culture.