Well, some people listen because they don't want to be rude and think that these people at least deserve to be heard. That was me.
To tell the truth, some other people listen to the witnesses because neither the adults nor your older siblings want to go, so "good ol' little one" gets to go. That was me for some time, too. That was back when the witnesses asked for a contribution, too, so sending the kid was a good way to spend only pocket money and get away with it. It's just doesn't look as bad if it is the kid who does that, right?
Moshe, you met very bad people :-).