We've also seen decades of effort, much of it successful, aimed at making it easier. Programming used to be harder. (Difficulty alone doesn't account for high salaries.) If it was never "the hard part", what motivation for all that effort? Books, pedagogy, tooling, languages, even the notion of publishing a library is an attempt to make coding a related task easier for others. There's been comparatively less effort in making "the other parts" easier. Though certainly things like software development methodologies count.