Oh please, this is the same type of nonsense that the Watchtower tries to say - that somehow the roots have some sort of evil beginning. Who cares!
This is 2015, these things have a different meaning for us. For us it's about letting kids having a little fun (minus the door knocking, i hate that), and about putting a costume, being silly, and enjoying it. Who cares if at some point in history some ancient civilization had some sort of agenda tied to this day.
Who cares if christmas trees, or wedding rings, or black cats had some sort of pagan ritual done by ancient and backwards civilizations. These things mean what we want them to mean.
The meaning for you may be different than the meaning for me, so......who cares if this is the stance I want to take. I was answering the original question, not soliciting judgement as I wouldn't pass judgement on someone who does want to celebrate. My kids get a candy pack at school from their teacher for Halloween, I don't take it away from them, but we just won't go trick-or-treating. I know this is a typical JW line, but kids can dress up, have fun, and eat candy at other times and for other reasons too, heck, my kids are always dressing up at home - this is just one of the things I won't be participating in and that's my choice to make.