For those who are tolerant of msg, it offers zero nutritional benefit. Banning it would help millions of migraine sufferers and harm no consumer.

You cannot ban a natural, ubiquitous amino acid, any more than you can ban salt. You can try to ban adding MSG to foods, but sooner or later, you would also have to ban yeast extract, soy sauce, tomatoes, hard cheeses, and so on, at which point we would definitely run into trouble.