The holiday was around long before 1990. Just because you grew up in that time and have overgrown it doesn't mean it's just suddenly getting old. I'm like you though, it's lost most of it's appeal for me, but at least you get to go to some interesting parties.
It's teh same for me, I'm growing up and I don't really feel like going out anymore. I mean I still kinda do, but it's just probably going to snow and freeze the crap out of me so I've decided if IT snows I'll stay inside and hand out candy to the kiddies, and if it's nice out I'll put on a witch hat and clock and get some candy.
I heard someone say that it's actually healthy for people to go trick or treating till age 18. I don't know how this works though I mean all teh candy...