The commercial CAD systems all have APIs to do the same kind of stuff, but they also have sophisticated UIs on top to make them easier to use visually. NX even lets the user record UI interactions as a function to make creating initial code faster.
In fact, there's a whole niche of CAD programming.
Tried Dune3D and was moderately successful, but couldn't see where in the U.I. such numeric/programmatic access would be afforded and it doesn't seem to be on the roadmap there either.
I suppose I should break down and buy Rhino 3D and use Grasshopper, or Moment of Inspiration and use its Node Editor, but for now, I've been using:
This is a sign that the software has grown to become its own operating system. They also have to add their own version control… remote editing, etc.
Unix style versions of tools are interesting in their own right (photoshop vs imagemagick).
Not really, though most of the commercial CAD systems are comparable in size to an operating system already. NX just spits out the journal file, it's assumed the dev will take the code and modify it to their needs using their normal dev workflow and their own version control, IDE, etc..