Does this offer anything besides circumventing the little set of features that VCV Rack charges money for? Am I subsidizing the development of this tool with my paid VCV Rack version?
One could argue that a plugin version is more than a minor feature.
Cardinal is not affiliated with VCV in any way. We use the upstream Rack source-code as a base so any support towards VCV will ultimately "trickle down" (in the form of code) back to Cardinal as well.
You can also use any VST plugin inside of Cardinal using the Carla and Ildaeil modules.