We don't need to wonder! They explain it right in the article: protectionism. It's not really that surprising that a lot of regulations have nothing to do with protecting the consumer and are all about protecting the parties that really matter to governments: big domestic industries.
> Around World War II, Carl explained, the established noodle industry (henceforth referred to as Big Pasta) was “upset” by the introduction of Nissin’s ramen noodles into the country, which were “completely out of spec” with what the United States then recognized as noodles — specifically because the ramen was being sold for a lower price and with what Carl called “lower standards” of nutrition. “They were really pressed,” said Carl. That’s when the “standards of identity” were created: Big Pasta made sure that all noodles had to meet certain specifications to be considered “enriched macaroni products” and sold in the United States.