Unfortunately, this story posits a question that can't be answered by the findings of the study. Why do we eat meat? My answer is simple, because we can. Humans are omnivores. Like the majority of great apes, we are opportunistic feeders who were more or less designed to do so. Our closest relative in the ape world are chimps and they frequently kill and eat other animals. From an anatomical and physiological perspective, especially teeth, all evidence indicates that the natural human diet is omnivorous.
So are we designed to eat meat? Yes. Do we have to? No. It is a preference. It is very hard to change peoples preferences. If it were easy, advertising companies would not be in business.
Essentially, you don't have to become a vegan, just eat less meat. Simple.