I think arguing about this is pointless. As a vegetarian myself, I usually try to avoid meaningless discussions like this... I'm a vegetarian because it makes me feel better not eating animals. Everyone has different morals and I don't think things like this should be forced upon other people. Do I personally think it would be a more harmonious life if everyone didn't eat meat? Yes I do, but unfortunately life isn't perfect and it's not ethical to think everyone could survive doing it. Food shortages plague many places in the world, and I don't judge any of them for eating meat when they have the chance.
As for the health arguments:
First of all, you can maintain a healthy diet regardless of your personal dietary preferences. There are unhealthy vegetarians out there and there are unhealthy meat eaters out there. Simply eating meat does not ensure that you will be healthy. Unless you are a health conscious person, you are most likely going to be lacking in some nutrients. If people choose to not eat meat, they can still get all the required nutrients using alternative methods, and there are many studies that can back that up.
Second, the majority of the meat you consume in your life is probably modified and artificial anyway. Using the "natural" argument doesn't really work. Humans are wired to get a certain amount of nutrients in their diet. Where we get that is not important to the body. If everyone was eating healthy free range animals, maybe you could argue that we are missing out on an excellent source of natural nutrients, however most animals on the market have terrible, stressful lives and are being engineered to create as much meat as possible. So I personally wouldn't consider what you're eating "natural".
Unfortunately, regardless of my opinions and thoughts, you will all continue to think the way you do, and that's my point. Discussions like this rarely get anywhere and normally just make us alienate one another. Regardless of your preferences, we are all just people, and we all have different morals. It doesn't make sense to force opinions on each other. Just stick up for what you believe in and don't let society tell you how to think. Whether you are happy eating meat or not eating meat, just do what's best for you and be aware of your decision.