OK. So, getting over my initial 'what??' reaction, which spun really rapidly through things like...
To do that, with MC, you're going to need the files imported to the library...
why would you want the cover art imported to the library...
why would you want back ups of your cover art in the library... (not necessarily)
to 'ach well, they can always be removed or otherwise managed afterwards' and 'I'm sure there's a perfectly good reason'
Let's get to it...
First of all, you'll need all the cover art files in that folder imported because you cannot easily browse the hidden appdata folder from within MC.
Once done, get yourself a file list that lists only those images. If you need help with this, just ask.
Select them all (this is why the previous step is important)
right click > Library tools > 'fill properties from filename'
Select 'Template'
Uncheck 'directories'
Check 'File name'
Under 'File name', enter [artist] - [album] (see attachment "fpffn.jpg")
Press "Ok" and MC will fill the Artist and Album fields for these files accordingly. Remember, if there are any illegal file system characters there, such as question marks etc., these will all be represented by an underscore. In this case though, the data will be used for creating folders, so probably not an issue.
Next, make the copies. Do this using the rename, move and copy' tool...
With all files selected, right click > Library tools > 'Rename, move and copy files'
Fill it out as shown in the attachment "rmcf.jpg". Pay attention to the top field. It defaults to "Move". Use the drop menu to change that to "Copy" (NOT 'copy and update', unless that's what you want.)
Press "Ok" and all your files will be copied as you requested.
That should be that job done.
Maybe try a couple before going wholesale to be sure you have it right.
Do you want the original cover art files to remain in the library? If not, select them, press 'Delete', choose the "remove from media library " option and press OK.
Seems a lot, but you'll probably do this quicker than it took me to create this post.
Good luck.
-marko