Apart from SVG, there are long-standing and well-established formats for vector graphics: Enhanced Metafile (EMF) and Encapsulated PostScript (EPS). Why not use them instead of a new file format?
IIRC EMF is specified as basically “whatever win32 GDI does”, it never was meant as portable format. And PostScript is a Turing-complete programming language - not really a way to make anything simpler, let alone SVG.