I think what I noticed about Conventions was this:
Since JW's don't get to go to proms or class reunions, basically fun and special occasions unless it is a wedding, conventions and assemblies make up for that.
So in comes the new hair dos, the new dresses or suits. It's the time that people can have mini reunions with people that they haven't seen in ages.
Are they showing off? I'm sure some are. But some are just enjoying whatever they can get out of life.