The only time it becomes more of a "craft" is focused purpose-writing.
While it may include moments of inspiration, the majority of it is just good old "elbow grease"...and your mostly constructing the song like any building project.
You have the idea, come up with a working plan/path, and then you get going on it, from the ground up, constructing each section as needed, etc. until it's done
When you are able to do that kind of songwriting with ease and regularity, and actually come up with songs that are pretty darn good overall....I think only then the word "craft" can truly apply.