I guess the wheel is supposed to represent a DJ's turntable (like you're the DJ in a club spinning a record). Keep in mind this was the original interface and at the time of it's debut the iPOD was marketed mostly to young people. Remember the dancing silhouette ads?
I love the wheel. In fact I miss it since now I use an iPhone so don't really carry the ipod anymore. I think it's fast and precise. I mean click click click click is slooooooooooooow.