Without question, it's gone down. When I first moved into my current neighborhood in 2007 (just before Halloween), we had around 80-100 kids come by w/families. It has steadily declined since. There was a small spike two years ago when it was a Saturday, but still below norms. I think parties and group activities at public sites have become the norm. That's probably good.
It was a good way to meet other families, so I will miss it somewhat. But times change. Probably this is for the better.