Animals that do eat meat kill for survival: whether that's protection or for food.
Killer whales will fling young seals about with their tails, apparently for fun, before they eat them.

While they're still alive.

On the other hand, I do not condone unneccesary violence or suffering towards animals. For example, I buy free-range over battery chicken, where possible. However, humans are omnivores. We do not have the proper digestive system to live efficiently off of vegetables (our appendix is vestigal, for a start, and we can't digest cellulose). The animals we eat are not self-aware, and if we didn't eat them, they wouldn't exist in the first place. Call it a symbiosis, if you like. We feed the animals, allow them to breed, protect them from predators and illness, and then we consume them. From a species point of view its a win-win. However, because these species are almost entirely dependant on us, whereas we are no longer entirely depenant on then, you could see it as a favour to the animals that we still raise them for food. Otherwise, evolutionarliy, they'd be toast.

Whew, that was longer than it needed to be...