Quality loss all depend on the icon, and most file / folder icons are fetched from the file so the quality is up the file, but there are a couple of file/folder icons that MC are providing. This icons must fixed.
But it is planed. But it is not just to change so it gets icon of size 24 instead of 16. There are also a lot of other fixes and changes to the icon system that are needed. And if icons are scaled there might be a performance issue. and the icons are used in many places and all places need to handle the new icon size.
24/48 icons have not had high prio since most user wanted to have 16 size icons since they wanted to be able to show as many files as possible.
But with the rise of user that are using high DPI mode then the need for more sizes have gone up.