The game does change, but using wood bats has never changed at the professional level. The wood bat has changed in some cases, but only wood is legal.
If injury proof is needed to prove metal is more dangerous, that "proof" probably isn't available in amateur baseball. You would need the same skill level players, hitting equally with both wood and metal. I do hate to think of what might happen if MLB was played with metal. Corked bats are illegal in professional baseball because they supposedly provide an advantage. Metal bats have had to change manufacturing standards because of safety, but technology allows for some to make a more lively bat than the competition, which IMO is more dangerous. Those would be the most popular bats. Competition forces maufacturers to create the liveliest bat. Manufacturers of the safest bat, haven't got a chance! Who would buy that bat?
I do think there is plenty of proof that more balls are hit hard with metal. We could base that on our own tournaments. The same exact teams and players get more hits and score more runs in the metal bat tournaments than they do in the wood bat tournaments against the same competition. The 7 inning games average 30 minutes longer with metal.
We also see the same hitters take bp and hit with wood and then hit with metal. The difference is mind boggling, especially in the frequency of hard hit balls. At the Metrodome in 2008 we had some balls hit out with wood. Rawlings sponsored a metal bat HR contest and all of a sudden balls were landing deep in the upper deck. (Same hitters, different bat)
And from a traditional standpoint, I actually believe that kids often prefer the wood bat. The largest tournaments (most players and most teams) in baseball history (on full size fields) are the WWBA (wood bat) tournaments in Georgia. Besides the 200+ teams in this year's 17U, there were over 200 other teams that wanted in this year. I think younger kids actually want to play the game the same way the "Big" boys play the game.
All that said, I still enjoy the game whether it's metal or wood. I really do believe the game is both better and safer with wood. The statistics that would relate to insurance companies might not show additional risk, but common sense and my eyeballs see it differently. Any advantage that goes to the hitter becomes an additional safety factor for the pitcher and others within close range and it's not always about getting hit by a hard line drive.
Maybe the insurance companies need to add up how much they are paying for arm surgeries for young kids these days. After all, there is no question that metal bats require more pitches. I actually believe this can be proven by checking the statistics in college regular season vs the summer wood bat college leagues.
Also I believe "Harv" made a very valid point regarding other injuries (which can be documented). We see many topics talking about overuse and abuse of pitchers.
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Wood bats will definately result in more ground balls, more shallow fly balls, less pitches per out, less pitches per pitcher, shorter games, less home runs and an increase need for "small ball" if you want to win.
It will probably result in less pitching injuries but, as a pitcher being struck by a ball sufficient to cause injury is already a rare occurance, being able to prove it would be like finding all 3 needles in that hay stack....you know their there but its hard to prove to someone who didn't see them go in there in the first place.
IMO, Harv's first paragraph speaks volumes about one reason why wood should be considered safer than metal. We will never eliminate risk, it will always be there. It wouldn't make sense to argue players need to "be tough" and except the risk, when the highest level in the world uses something completely different.
As far as politics and government involvement in baseball, I don't know what to think. That's another issue all together. BTW, Do the environmentalist have an opinion on the wood vs metal debate?
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We even have video that shows those hitters with metal and wood.