I've always been against the modern 14-12 slugfest. I'd much rather see a 4-2 game. One: It's more exciting, Two: Pitching actually matters. While I dont think a metal bat will turn a poor highschool player into Barry Bonds, it will help with the bat speed and the power.
But that brings up a safety issue. If a ball comes off of an aluminum bat at 100 mph (just an estimate) as opposed to 80 mph from a wooden bat, thats a big difference. It can mean the difference between getting hit in the face Bryce Florie style and making an out, or dodging an oncoming ball.
I think wooden bats should be used in all levels of baseball. It makes for a better game, better pitching, and is much safer. Plus, the sound of a ball hitting a metal bat is annoying.