Visual code generators have existed for two decades, most famous is the Rational product. I've never met a developer or read an unbiased article claiming that the code generators have helped. Usually they say it just leads to ugly code and high maintenance overhead to maintain the diagrams.
In natural language, why haven't photos and videos replaced words? It's because words are still the best way to express precise and complex logic. Now, it's up to the writer to express complex logic in a series of simple steps that a reader can understand, or to write in a convoluted way.