Yes, too true. Sometimes vegetarians and especially vegans do more harm to their cause, with their judgments and criticism of omnivores. It can be a turn off for those considering the vegetarian or vegan diets for whatever reasons they were thinking about. And for those not even considering it, they get the feeling they are being judged or worse -- being called evil.
I have been vegetarian and mostly vegan (for over 28 years) but understand it is a personal choice and even if it could be proved beyond all shadow of a doubt to be the best for nutrition, the environment, etc., the power of tradition and culture is very strong that people would not easily change the diet. And it is no use to impose our values on others. It is not useful or wholesome. My own thinking and writings have been more tolerant and more accepting as time has moved on from the first time I became vegetarian and even since writing that book.