An issue for local meetups is notifying users not signed up or checking their watchlists. Adding city level geo-targeting means we can be more effective in our reach.
WM-NYC serves 20 million people within 2 hours of travel (60 miles/100 km) and regularly has meetups. National level notices are inappropriate and outside the chapter's scope. The last time one was run (Wikipedia 10 birthday), the response was 5-10x. Most new attendees are the result of flyers and not website interaction.