As Joshua Rosenthal says in Integrative Nutrition, "Nutrition is a funny science. It's the only field where people can scientifically prove opposing theories and still be right." We are each biologically diverse and there are many factors that may contribute to nutrition study findings. Correlation is not the same as causation.
For me, personally, I get irked when people tell me that all humans should be vegetarian, and the only reason to eat meat is because it tastes good. I can tell you from several years of personal food exploration that I do not do well on a vegetarian or vegan diet. I get bloated and lethargic when I eat too many grains, or any legumes at all, which are primary sources of non animal protein. If I don't get enough protein I get serious blood sugar drops and spaciness. I am not alone in this. I know quite a few people who have had the same experience, including some who spent a significant amount of time eating vegan, such as this person. I once happened upon an article from a woman bemoaning the fact that our environment was so toxic that even on a perfect vegan diet she still suffered several autoimmune issues refusing to consider the fact that maybe her diet wasn't so perfect for her after all.
Now don't get me wrong, I'm not against vegetarian or vegan diets in general. If you are on one and thriving - that is awesome! I'm just saying that it can't be assumed that it is the perfect diet for everyone.
If you are concerned for ethical reasons, I totally respect that. I found this article interesting. It does not condone factory farming, but it looks at the ethical issues of farming from a perspective I hadn't considered.
I myself have found that something close to the Paleo diet, or "Perfect Health Diet" seems to work best for me. When I first discovered the difference it could make in my energy and health, I wanted to share it with the world. I realize though that what works for me, might not be great for everyone. When people trash the concept though they are not seeing the people for whom this diet has really transformed their well being.
Most of us know these days that cutting out processed foods and moving to a more whole foods based diet can have a positive affect on our bodies. Everybody has different needs though when it comes to proteins or processing different types of foods such as grains, legumes and dairy.
Please do share your own experiences with food, but lets make a deal - don't tell me I'm wrong for eating meat and I won't ask you where you get your protein.
