SVG is awesome... but this is a basic enough subset of SVG that SVG is unwarranted. CSS will do this just fine (and any browser capable of displaying this SVG can probably support the CSS features required to pull this off).
However for those that: 1) Don't want to 2) Don't know how to 3) Required rendering besides HTML views
This can be pretty useful :-) I do agree with you. I would actually consider adding SVG support to this as well.