I would like to go into more detail on the bats, as I know may people do not agree with metal having more power. Yes, if you used a machine to hit the ball, a wooden bat may actually carry the ball a bit further after a big contact. However, humans do not hit with that kind of maximum consistency and most players are not big hitters; so the speed with which the ball comes off the metal makes seemingly minor contact, quite major. Contact that might not normally carry out of the infield ...does so far more often (to the delight of friends and families of youth players everywhere). Hits that would be simple outfield catches with wooden bats, now go over the fence much more often.
Then there is the money. College coaches in the Southwest and South all can easily make 10's of thousands of dollars from Louisville Slugger and Easton (the two primary bat manufacturers). As can many coaches in the rest of the nation with CWS history. In short, Kids hit metal because parents like to see the action and Louisville Slugger wants parents to grab their bats off store shelves.