Users demand semantics/logical editors. They do not care about underlaying XML (but they are proud of their indentation if they text-edit it). It may require semantics models or declarative description of UI presenting generic XML model.
ARCHing it as it may result into a framework. APIng it is I expect a public contract. It may depend on issue 26478.
*** Issue 28065 has been marked as a duplicate of this issue. ***
XML tree editor is not part of NetBeans since 3.5 version. No plans to bring it back.
Verified - done long time ago