Documentation is great, but the real benefits from writing docs aren't the docs.
Maintaining R packages on CRAN sometimes means you have to find creative ways to ensure that your code runs on different platforms and on multiple versions of R---even ones that haven't been released yet.
You don't have to be a web developer to have smooth flow and consistent style across your personal website or blog and your R package websites.
Building a beautiful website for your R package is a great way to improve its documentation, usability, and visibility. 'pkgdown' makes it easy to build your site, particularly if you follow these conventions.
Here's the story of the time I wrote a R package for an undocumented web API in under an hour, with documentation and full test coverage. With the right tools, creating an API client can be quick and painless.