I've noticed the same problem. In quite a few drop test videos I've watched, the camera lens cracked before the screen. I have the Urban Armor Gear and it provides some protection by adding a small lip around the camera. At least it won't get scratched when I use it on a flat surface. But I haven't come across any cases that offer additional protection for the camera.
What I can tell you is that the replacement lens is pretty cheap. I think around $10. It seems like something an average user can replace themselves.