MOST vets and snake groups I know of DISCOURAGE feeding live food to a snake. Snakes can have major harm done to them by feeding live, including fatal infections caused by rat/mouse claws/teeth. Yes, it is natural for a snake to eat live prey, but it is not natural for even if it doesn’t feel like eating that second the prey is stuck in an aquarium with it and will fight for its life. Also, in the wild, if a snake attacks prey that is too dangerous and hurts them to the point of death, well, too bad for the snake, that is nature.
To give you an example: my brother had a pet fancy rat (looked like this guy: http://albertarats.webs.com/3608.jpg) when I was a kid. We lived in Florida, on 5 acres of land, with a pond in the yard. Lots of snakes in the wild around our home. My mother put in a doggy door for our dogs, we had a fenced in yard for them and she got tired of getting up and down to let them out every time they wanted (up to 50 times in one day). A rat snake (http://www.snakesandfrogs.com/scra/snakes/brat.htm) came in through the doggy door one day and got into our rats cage, this was early morning so no one was in the living room where the rat lived. My father hears the dogs and rat making a huge fuss so goes in to see what all the noise is about and … theres a snake bloodied face being beaten up by our rat. Harm to the rat? A lost claw, which was lodged in the snakes face near the eyes. The snake was taken out and set free, the rat was checked out and fine. He suffered no ill from his encounter, except a sore foot, which healed up in a few days. Yes, measures were taken to keep snakes well away from him after that, no one was thinking about wild animals coming in the house through 5 dogs to try to eat him.
Beyond the danger to the snake, it is considered not very nice to the animal that is prey either. Feeder mice/rats that are sold frozen are humanely killed and then sold as food. I personally could not own a snake, but then my pets are all vegetarian just like me. I have issues feeding dead things to anything, including myself.
But… unfortunately many animals, yes bunnies included, are considered food. People still eat rabbits for human food too. It isn’t any more wrong than eating any other animal (and how wrong that is, is up to each person to decide themselves). Yes, we all love our bunnies, but there are people who love their mice and rats just as much as we love our rabbits. There are even people who love their chickens, pigs and cows as much as we love our rabbits. That doesn’t mean anyone who eats meat is evil, or anyone who feeds those animals to their predator pets is evil.