Hi Tracey, 
Welcome to the list and thanks for coming out of the (lurker's) closet.
1. Because we eat mostly grass-fed meats, the animals that provide our meats
don't live in the ugly conditions of a meat factory. 
2. Weston Price and Paleo are both venerable paradigms, but there is a lot
of solid science that falls outside of both of these perspectives, and may
yet prove crucial to healthy eating, especially for those whose genes are
partly or wholly non-European. 
3. Grain production causes salinization of soils and desertification of
grasslands. 
4. Have you ever considered how much of various vegetable crops could be
produced from the same acreage it takes to produce a given quantity of
grain? 
5. Have you ever considered how many ruminants, grazing a given meadow would
produce in pounds of meat per year, as compared to the production of grains
from the same area? And bear in mind that the meadow's nourishing capacity
could remain fairly stable, without need of chemical fertilizers, etc., and
all the fossil fuel consumption that grain operations require.  

The economies of agriculture can be quite inscrutable, in part, because of
government subsidies. Very marginal lands that won't grow cash crops can be
quite economically used as pasture for beef, mutton, etc. If the same
government subsidies were aimed at meat production, over a similar period of
time, we might be talking about the uneconomic nature of grain crops. 

Finally, as Wayne pointed out, we will all soon be worm food, beginning yet
another cycle. Ethical and sustainable Paleo may, arguably, be dependent
upon a shift in public policy. In the meantime, I think that grass-fed
meats, free range eggs and poultry, are as ecologically friendly as any
other choice. 

best wishes, 
Ron