That said, I usually don't minify my CSS anyway. I was just wondering if there are any significant cases where comments would make a huge difference to someone who is learning CSS.
Not sure how much though.
Expecting comments in css to act as some sort of tutorial is a dead end, any website will involve html/css/js working in tandem, why put them in css, rather than html, or js?
A better format for this would be a number of good old fashioned tutorials, screencasts etc geared toward providing the mental tools to inspect any website.
So, sure it wouldn't be much work to add in a comment pointing to an unminified css file, but i fear it would be of little utility to someone learning. That is ignoring the fact i often have 20+ css files across a large site (minified compiled and combined before serving), similar number of js resources and who knows how many combinations of html templates...