I guess I disagree that it's a good thing.

As a developer, I think most documentation is terrible both for developers and non-developers alike. And if you write your documentation so that it is useful to non-developers, it's still useful for developers.

There's no downside to writing accessible documentation, except that it requires a modicum of skill and effort. That's the real reason it's so rare, I think.

I also disagree that developer documentation is like academic papers. The ways they fail are almost opposite: academic papers are overly long and overwritten, because the authors want to be very careful and complete. Developer documentation is too short and hastily written, because they often don't care if it's helpful to anybody else.

The end result may be the same: neither are useful except to a small number of experts: the people who could probably do it themselves already, and thus may not even really need the write up to begin with. But that's a failure, not a feature to be celebrated.