The problem with that is that you still need to implement a full XML parser. Even if you strip out any CSS and ECMAScript, it will still require the complexity of XML with all it's gloryness and escapiness and ambigious defines.
And even if we rely only on XML, we get the DOM and hierarchical structures. If we forbid those, we have <svg><object /><object /><object /></svg> as a file format and people will look weird because their other SVG won't be supported in there.
And even if we rely only on XML, we get the DOM and hierarchical structures. If we forbid those, we have <svg><object /><object /><object /></svg> as a file format and people will look weird because their other SVG won't be supported in there.