I don't follow the logic here. If you refrain from doing something unethical, aren't you by definition behaving more ethically than you would be otherwise?
The main gist is that people to me are not very ethical. Becoming a vegetarian barely scratches the surface.
By refraining from doing something unethical I think we can be unethical. Lions kill, so to oppose their extinction supports killing. That's an example.
Human ethical choices are almost always compromises -- like weighing two rocks against each other. Human A lives in comfort in a city, burns fossil fuels, opposes the burning of the rain forest. Human B lives in the rain forest, is always itchy because of mosquitoes and in danger of snake bites, favors burning the rain forest but wants to make cities create less co2. Pure ethical considerations are warped by the concerns that someone focuses upon -- because ethical decisions are often compromises. In other words the ethical decision balances the pros and cons, and what is pro or con can very upon where you live and what matters to you. This is also true for considerations about what to eat.
Here's an example of an ethical dilemma. A raccoon keeps upsetting your garbage. Do you lock up your garbage can or do you keep letting the raccoon eat from it? Most people would lock up the garbage can and consider that raccoon a nuisance, but wouldn't it be more ethical to feed the raccoon? Maybe its more cruel to encourage it or more cruel not to feed it, but the raccoon is such a nuisance that its hard to think clearly about the topic. One may come to a decision about what to do, however the ethical considerations are weighted rather than starkly obvious in every case.
Now consider that you are kind to animals and your children, but you ignore the needs of orphans and strangers. What is so ethical about you, then? Its not such an extremely ethical life, and its a typical human life. Its not convenient to care about orphans. Its not convenient to care about strangers. Convenience is the death of ethics, but humans are extremely interested in what is convenient. What we eat does not change this. It does not make us much better at all.