I too write documentation. Not exclusively, but in my day job I often write manuals and other documents for our software, and I've done documentation work as a volunteer for Project GNU.
It's no more strange that someone would enjoy writing documentation that it is that someone would enjoy writing software, though just as non-developers don't understand the joy of programming, I imagine that non-writers don't understand the joy of documenting.
So a question in return... Do you share my belief that documentation tends to lag in most projects? And if so, is the bottleneck not enough documentation writers, or not enough engineering time and attention? I've assumed it's the latter, though it could be the former. Or is it something else?
Do you share my belief that documentation tends to lag in most projects?
Absolutely.
I suspect that the number of people interested in writing software documentation is fairly small: they have to have enough knowledge of software engineering to be able to understand what they are writing about, and they have to be good writers. Anyone could learn software development, but not everyone does. And anyone could learn how to write well, but not everyone does. So the set of people who learn both is even smaller.
On commercial software engineering projects, my experience is that documentation of any sort is made as much of an afterthought as possible, if even that. Unless there's some business case (i.e., obvious money) that comes from spending time on documentation, then it doesn't make it very high on the priority list. Which is unfortunate, because as a software developer, I've wasted a lot of time figuring things out that should have been documented. So money can be saved later on, even if no money is "earned" up front.
For free / open source projects, the story may be different. There's not necessarily paid engineering staff involved, so if documentation doesn't get written, I can only presume that the developers either didn't want to, didn't know they should, or felt incapable of writing it. I find it hard to imagine taking a principled stand against having good documentation.
BUT... in my anecdotal experience, I've encountered volunteer open source software developers who in fact did seem resistant to accepting offers of volunteer help with documentation. So I'm not really sure what's up with that.
It's no more strange that someone would enjoy writing documentation that it is that someone would enjoy writing software, though just as non-developers don't understand the joy of programming, I imagine that non-writers don't understand the joy of documenting.