Thanks again for the feedback, it has been implemented in the currently live version of OctoShaper.
I am archiving this post as I've created a dedicated official thread for user feedback.
Thanks a lot for the suggestions!
The tool will probably release in July on the Asset Store so I don't plan on making this open source.
But, I'm taking all your suggestions and I'll make sure to include them in a next release. Also, you'll be able to create custom nodes using a public API so this should unblock you.