This extension is a nice step in that direction but still involves copy/paste and editing.
It currently outputs CSS based on the filenames from the sourcemaps, theoretically you could append the changes to the same files via a webpack plugin, and then if you ran it through some step after to make the selectors appear in the right place in the file, you would get the experience you describe, where it's like you edit the CSS in chrome and it saves it to disk directly so you can commit it later
Seemed like too big of a jump though to start off with that, because first asking people to install a Chrome extension is a thing, and then not everyone uses webpack for front-end and I'm sure there'll be complicated edgecases with something like this