- smaller carbon footprint (more efficient to ship pork than grain to feed pigs)
- more efficient use of by-products
- superior taste and texture
- more humane (Temple Grandin has worked on Iowa slaughterhouses)
(The commenters say: well, Californians shouldn't eat pork. Or they should accept the ununiform taste and texture of pigs fed a varied diet.)
IMHO, if you accept these arguments, you accept something like a global agricultural system, because similar arguments can apply to other foodstuffs.