I'm going to sound like Richard Stallman, but being human-readable and Notepad-accessible is a huge advantage for SVG compared to this and its binary nature.
It's optional, so if the need you identified exists it will be implemented. Its essential selling-point is compactness, so being the target, the path of least resistance should be optionally allowing the text-form, not building around it.
I think there is a place for rich text and compact binary formats. Then can pre-render from complicated source to produce smaller and faster binary format. You would edit the SVG and then make TinyVG (and minified SVG).
SVG is weird among image format in that it is XML. It requires a lot of effort to parse and render.
What does "Notepad-accessible" mean? Surely you're not referring to notepad.exe in a sentence beginning with "I'm going to sound like Richard Stallman"?
