Comment 1 for bug 1739230

What would be the use case for this functionality (or rather what part are you missing that could not be covered in a better way by one of the metadata fields available in the document properties)?

Do you want to add a single comment somewhere at the top of the file or would you want to add comment nodes at arbitrary positions of the document?

This is also something that could likely be solved by using an extension.

As a workaround you could even add custom attributes to objects in the XML editor.

Reasons I'm a bit skeptical this would be useful for many users:
- XML comments are invisible for most users
  (most of them would not even be aware of them)
- XML comments are not really suitable to carry metadata
  (thats's what <metadata> is for)
- XML comments are not bound to XML nodes making
  their meaning kind of open to interpretation
In conclusion XML comments are mostly useful for humans looking at the text representation of the XML source - and that is not really how Inkscape is meant to be used.