I've been trying to apply this approach, and it's generaly been a useful way of forming a holistic view of your docs.

The only quadrant that can be a bit challenging is the explanation: some projects are just relatively straightforward and don't require a lot of background knowledge about the whys. In that case, I've found it best to just stick to a couple of lines on the homepage explaining the project's background and the problems it's solving, rather than a separate, rather barren-looking section of your docs.