I think of this debate as one between the welfare of different species. On the one hand, it's good for the welfare of the predator to give it live prey so that it can engage in natural behavior. On the other hand, it's not good for the welfare of the prey because it dies, sometimes brutally and painfully. It seems that the majority of people place more import on the latter.
It's not just that, don't forget the majority of hunts fail in the wild. Furthermore most prey is capable of causing injury to the hunter. This risk/reward is part of life; but if you're conserving endangered animals you really can't risk your bed breeders or your new line being endangered by feeding practice that could cripple or kill them. So there's an element of protecting the hunter as well. And whilst some could argue that you could drug the prey, lessening risk on both sides, but then you have to ask what the value is; a drugged prey is akin to a pre-killed one - its not going to teach that much of the hunt to the hunter.
