Being a meat eater was not a 'decision'--so to speak, at first.  I was raised eating meat--It was a no brainer.
When my hubby and i first started out, money was tight, so I started experimenting with  meatless meals.  We still eat meatless meals occasionally. I'll get back to this in a moment.
Having a 'hobby' farm has always been a dream of mine--one that is now coming true.  But up until now, I knew of the conditions of commercial meat operations, but still 'chose' to eat meat.  But doing so made me want to live my dream out even more.  If I couldn't raise my own animals, I would still eat meat.  And yes, I would eat the meat that the grocery stores have on sale.  (Money is always an issue for me.),  and i would eat it without conscience.  
Do I like how animals are treated in commercial operations?  No, but the reason 'they' exist is because of supply and demand.  With industrialization, not everybody could or would produce their own food.  T hey(we) had to get their (our) food somewhere and of course(we) had to have it the cheapest.
Now, as with most things in 'big business'  ppl find things to complain about.  Too much pollution, chopping down forests, commercial meat production, GM foods, it will never end.   And we as humans will continually make stupid choices 'for the betterment  of society', until hindsight sets in  (yeah--lead in paint wasn't such a good idea etc) 
Our family hunts, and some ppl find that immoral.  We are Christians, some ppl take offense to that., but I have permission from My God, to eat meat.  To each their own. I will never condemn anyone for their choices--of religion, of whether or not they eat meat.  I just know that I, with a clear conscience, eat meat, will continue to eat meat, and will feed my family meat.  If i didn't enjoy the 'hobby farm' life, I would eat meat that I didn't raise myself.
Oh, and does vitamin B12 come from plants?  It is extremely important to the human body, and unless I am wrong, it can only be obtained from meat.  
Following up on the 'meatless' meals I made--and we only ate meatless 2 or 3 times a week, i developed  B12 anemia.--to the extent where it did a little damage.  I thought I was ok, since we still were eating meat.  and supplementing with vitamins.  turns out my body can't absorb the vitamins in pill form.  Guess what my doctor told me to do?  That's right--eat meat--lots of red meat.
I gues my point is--its not a moral issue for me.  I eat it b/c we can, b/c we were made to  (our teeth and digestive system), and b/c my God told me I can.  I eat it b/c I like it., and b/c my doctor told me to.  That being said--I do like it better that I can eat the meat that I grow. myself.  But I would still eat it if I had to buy it from the grocery store on sale.
i think the only thing that makes me is honest.
Disclaimer:  no offense was meant to anyone by any of my statements.  Jus tpassing along my point of view.