If the statistics given by Little League in the first post are accurate, then I don't see the problem with aluminum bats in Little League. Even if PGStaff is correct in saying that wood is safer, the difference is so small as to be statistically insignificant.
I think little kids learn how to pitch faster than they learn how to hit. I would let the kids continue to use aluminum. It makes for a more level playing field. Also, after having coached and watched tons of youth games, I can tell you that more kids get hurt from thrown balls than from batted balls. And that's not including pitched balls.
Once the kids are H.S age and older the issue becomes money, not safety. With the present system, colleges could not financially switch to wood bats. Major League baseball would have to subsidize the colleges, which they have no intention of doing.
I would love to see College baseball go to the wood bat. It would extend the life of a lot of college pitchers arms. And the games would play more like the Major Leagues.