I'm an adult. It's less about not wanting to dress up as it is not having to dress up. Miles just turned two. I have another year before he's really into it. I'd dress up with all the face makeup... make a big production out of it, and I'd end up scaring him. All I have to do is walk with him around my sister's neighborhood (which has WAY more children / Halloween spirit than mine). It will be exhausting, especially with a pregnant wife. When he's into it, I'll have to start dressing up again, decorating the house, etc. Might even have to buy some inflatable lawn art and, god forbid, carve a pumpkin.
Friends all have kids, so there are no Halloween parties in my social circle. We just party every weekend during football season, no dressing up required..