Posted about this kinda issue way back in 2013...
https://forum.kodi.tv/showthread.php?tid=163814
Since then, there have been great improvements within Kodi regarding these issues (a lot of that is beacuse of DaveBlake, Helta, Scott967, etc).
I would say, if you truly want to fix your issue, there are 2 things you can do (which require a little bit of work on your part).
1. Download Artwork Beef (
https://forum.kodi.tv/showthread.php?tid=258886), and have it go through your Music and download all the art.
2. Download MediaElch Media Manager (you need the nightlies, which you have to donate to get), but the nightlies have fixed the Music settings (currently can't scrape with the free version). This will provide you with all the Artwork, NFO files etc, for your Music. Of course you can still run the free MediaElch, and see your Music Library, and you can manually download and adjust your Music to your hearts content, but that's a lot of work on your end.