I started out a knight, you know the reason? Well I was about 12, and rook and bishop sounded stupid... So I said that I'll be a knight because they sound cool.
OMG!!! That's it! All the little kids go to knights because it sounds cool. If not knights they go to rooks because really, bishop sounds queer. All the old people realize that the little kids don't want to go bishop so they all meet there (explaining the high numbers) and there you go!