In the US, the number of days per week that people in the under $25,000 income bracket (2012 data) consume meat is approximately the same as in higher income brackets. It seems very plausible to think that what makes this equality in the consumption of meat possible is the affordability of meat resulting from factory farming.
Suppose this is so and factory farming were eliminated. Then, there might be little change in the consumption of meat by people at the top of the income scale, as they could afford meat from small and expensive operations, but we would expect a significant decrease in the consumption of meat at the lower end of the income scale. Since people’s feelings of happiness and misery are largely tied to comparative evaluations, this inequality would be likely to lead to increased misery in those at the lower levels of the income scale who are already living lives of quiet desperation.
Moreover, observe that the impact that a pleasure has on a life intuitively depends on what other pleasures are available in life. Suppose I ceased to eat meat. But my own life is really great, and opportunities for pleasure abound. I have a wonderful family, a really fun job, access to Baylor’s incredible recreational facilities, books, video games, microcontrollers from Aliexpress, and enough leisure to enjoy all these. Losing regular access to the gustatory pleasures of meat would make only a small dent in my subjective wellbeing. (It would mostly be a nuisance: I would have to think harder how to fulfill my high caloric needs.)
But imagine that I am really poor. I am trying to support my family by holding down multiple low-paying jobs. There are few pleasures I have time for in my life and much stress. In that context, losing regular access to meat would take away one of the few pleasures in life—the pleasure of eating meat with a regularity that in the past mainly the rich could afford. Moreover, the pleasures of eating are often not just solitary pleasures but communal: I would lose sharing this pleasure with other family members living difficult lives.
In other words, the elimination of factory farming would have a highly unequal effect: the rich could still have their meat, and meat plausibly makes for a much smaller contribution to the well-being of the rich given all the other opportunities for pleasure available to them; but the poor would lose much of their access to one of the much smaller number of pleasures in their life, which would be a much greater loss.
Now, of course, an argument like this won’t justify every inhumane farming method in the name of making meat available to the poor. But it seems to me to be a serious argument in favor of some factory farming practices. Moreover, there is here a positive, albeit weak, argument in favor of even those of us who could afford meat farmed more humanely to eat factory farmed meat: in doing so, we contribute to the economies of scale that make meat affordable to those in lower income brackets to a historically unprecedented degree.