IE <= 8 and Android <= 2.3 don't support SVG without a polyfill[1]. For much of the web, IE8 is still the lowest acceptable version of IE and Android <= 2.3 is still about 40% of that market. You may be able to use it in your projects, but there are still many people who cannot yet.
[1] https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Brow...