Idea Summary
If you persist a css or js file, a minified version is created. If you on the other hand import a file, lets say from a GIT repository, this is not the case. This is problematic if you set the link to use minified file versions, as the minified version is not updated if you replace the full version with a new one.
Use Case
The mentionend problem arises if you are working with more than one environment or if you use externally managed files in more than one application. Without creating a minified version, you are forced to open and save every single file to create an updated minified version.
Preferred Solution (Optional)
Two solutions: If you create or overwrite an existing file, APEX could create a minified version automatically. If this is not possible, a button to create minified files for all files could be added.