As my old boss used to say “we’re singing from the same sheet” 
Yes I’m definitely for an incremental approach.
I think that it is worthwhile for us to consider to bigger picture about where we would like this to go, even though implementing it will depend a lot on how Audacity works internally. At least we can paint a picture for the developers of how we would like it to go.
Nyquist versions are currently up to “version 3”. The possibility of a major new variable could be introduced as a feature of “version 4” plug-ins. Audacity already checks the plug-in version number before loading the plug-in.
The Audacity MIDI features are very much “Experimental” and are mostly the work of Roger Dannenberg, the same person that invented Nyquist.
Have you seen the “Nyquist Wish List” post? https://forum.audacityteam.org/t/nyquist-wish-list/15530/1
I was wondering how to go about presenting the ideas in there. Not all of the ideas there are good ideas
Perhaps a good approach would be to propose a specification for “version 4” plug-ins?