There is nothing inherently bad about slaughtering animals for food, if one accepts that humans are omnivores and some choose to eat meat, and if it is done appropriately. However, I play this game because I like to pet my animals. I don't want a whole part of the game set up around killing them. I like the fact that they can live forever, and I can pet them every day and get a little heart. They will never die. In real life, I rescue very ill rabbits and nurse them back to health, if I can. But even the ones I succeed in saving will eventually die of old age. This game is an excellent escapist fantasy, where my rabbits can live forever.
If someone makes a game around more realistic ranching life, where some of the animals are turned into meat for food, that's perfectly fine - for other people. I merely have no interest in such a game, and am expressing that.
This was going to be a feature, but CA decided against it so I highly doubt he'd consider ever truly implementing it if he already decided not to have it