I've used embedded SVG images in CSS encoded as base64, and I'm not ashamed. In general, I really wish I could apply page styles and CSS3 variables to the internal CSS of SVG files. I'm sure there's a good reason why this context isn't shared, but it would be cool and useful to dynamically change the style of SVG files.
If I'm hand coding a page or writing a stylesheet, it's convenient to be able to embed things. Often, I'll embed a style tag until it grows large enough to be worthy of its own file. The same goes for scripts; it's useful to have the option if you're quickly prototyping something.