It was a little more than just kinaesthetic (if I understand that term correctly) - at least for the 'core' navigation keys. [...] This idea of placing the commands to mirror the action works well enough that I could remember the actions of those particular keys even after not using the Wordstar layout for more than a decade (which I think is unfortunate, but I got tired of fighting to have to configure every last bit of software to respect the Wordstar commands).
That's true, there is an "intellectual logic" to the WordStar Diamond, if not always the other keys.
It's one of my grievances against Microsoft that they pirated WordStar keys for other things, Ctrl-C, Ctrl-X and so on. There are a few Windows editors that can be configured to use them - e.g. WSedit
, freeware by Dr. Martin Vieregg. That's one of the most extensive sets I've seen.