That's a pretty absurd complaint.

Are you aware of any XML parser ever which preserves the plaintext formatting of the .xml file while magically inserting and modifying an arbitrary amount of XML data anywhere within the document?

SVG is just XML. Save your file in Inkscape, and then run `tidy` on it, or whatever you like for format your XML with.

(As a fellow hand-crafted XML fan, I feel your pain. But I also know when to choose my battles!)