I've looked in to this, but the main problem is there doesn't appear to be good browser support for rendering SVGs in WebGL mode. Most of the example code I've seen involves rendering SVG to a fixed size texture then rendering that in the game, which will cause an extremely high memory usage. Even if direct rendering worked, high-quality SVG rendering can involve hundreds of vertices per image, whereas a textured sprite is always four, so it would likely have a performance impact noticable on mobile.
Ordinary textures are actually pretty fast, memory efficient, and well-supported in comparison. You can still design resolution independent games by rendering artwork for your highest target resolution, and then mipmapping ensures high-quality downscaled rendering. SVG is definitely something we're keeping an eye on but I don't think it's something we could add in short order.