The problem with cover art embedded into MP3s is that the same image is usually inserted into every file of an album, unnecessarily wasting space on your HDD or mobile device. To remove the extra images and optionally save them as cover.jpg, I use the free program named taghycardia.
Select a bunch of albums and drag and drop into taghycardia.
Press Remove Art and confirm the removal.
There you go: the program has removed all cover art from your albums saving you several MBs of storage space.