I know some people who have chosen to be vegetarians for health reasons, many were meat eaters for most of their lives and due to serious health problems, their doctors recommended they discontinue eating red meat and fatty meats.
While others are socially conscious of the cruelty that some farm animals face in order to be our food.
So I think it can be a proactive choice to try and be healthier, but not all vegetarian dishes are healthy, some contain high amounts of fat, such as cheese, heavy sauces, butter, creams and egg dishes and white bread. Also one would have to be careful of too many carbs as well.
Many have chosen to be Vegan to eliminate the dairy products from their diet. Getting enough protein will always be an issue for vegetarians.
I would suggest if your a vegetarian, vegan or not either way "balance" is necessary to eat right.