Still in my point of view it's immoral to kill. All the land used for animal feed could be used to produce plant-based food...
And yes, I totally agree: one or two cows at the farm lives a happy life, gives maybe birth to a baby cow, will give 90% of the milk to her baby, which will not be taken away from her and 10% goes to the farm-family. This is balance and I would say moral. Same with chickens etc.
But this is sadly not the norm anymore. And yes, I also agree, that monoculture is not good at all. But the food fed to cattle is mostly produces in a mono-cultural way...We got to find a balance again