There's also real-life, practical considerations. We're not going to do anything about the population problem, and we're certainly not going to feed 7.2 billion on grass fed anything, lamb or not. Fish were probably our best shot at "meat for the masses" - as it has been throughout history in many places - but we've done goofed there.
I'm finally getting to a financial point where I really COULD opt for getting almost everything organic, grass fed etc. Just a little longer and I'll be bloody golden. However, that would be a brief candle, before the movement expands outwards and prices get well beyond my means.
At least there's rice and synthetic vitamins :/