Marc has the basics of it. Generally speaking, real bows were removed due to issues with the bows themselves. People would block with them, cutting into foam, the bow tips aren't padded, and padding an actual bow leads to massively reduced performance. I would disagree with the arrow breakage issue... aluminum shaft arrows don't break without someone really trying, but they do warp, which leads to poor accuracy, headshots, groin shots, etc. A straight arrow is fine, but people have a tendency to want to swat them out of the air, which leads to the warping problem.
One of the other problems became more prevalent when Amtgard shields, which tend to be padded and thus have more "spring" to them, would block the arrows, causing them to fly straight back, with the nice, unpadded nocking tip headed to nearby meleeists.
In the 16-some-odd years I've played, I 've only seen two "unreasonable" injuries due to bows. The first was from the nock-bounce problem, which hit a player in the eye, and the other was due to a player insisting that their 30lb pull compound bow did not pose a prevalent increase in power, who then shot an arrow that another player blocked into their own crotch.
There have been sucessful experiments and uses of "golf tube arrows" and other similar devices, but NERO, both International and Alliance, is slow to change it's opinion of bows as unsafe.
