Not eating meat is a simple decision. But feeling morally superior to those eating meat is a problem. Especially when the meatless lifestyle is defended by saying to save other creatures' life, yet the same lifestyle is heavily supported by products which were grown in large monocultures, destroying the natural habitat of countless critters in an otherwise rich flora and fauna all over the globe.
Both lifestyles require monocultures. One more than the other actually, and that same one also requires more water and land, and creates more pollution. I'm not a vegan, or even a vegetarian, but I think it's objectively true that those diets are morally superior even with animal rights aside.
