My Wal-Mart was the same. I went to get my GameCube, and there was nothing going on in the electronics section. Everyone was milling around, trying to figure out what to do. One way or another, we figured out we needed to go to the service desk. Employees handed out tickets of some kind, and people who had reservations (I wasn't one of them) were understandably ticked that they were now waiting in a huge line for theirs just like everyone else. If you reserved and didn't show up in time, I'm sure Wal-Mart didn't bother keeping a system for you.
I don't think it's for kicks, I think they just don't have a true reservation system in place. They probably just give out rain cheques. So you prepay for the priviledge of standing in line like everyone else. What really got me about my experience was that it came like a week after the Xbox launch. I would have thought they'd be more prepared.