Took me about (in theory) three clicks to embed all my artwork 😉
TagsRevisited has an option (screenshot) to automatically detect and embed artwork (including folder.jpg, ..Album name (front).jpg etc.), at least for mp3s. Just browse to a music folder, check that art is now included, click save. I did it folder by folder, but in theorie you could load the whole collection at once, click save and go away for a few coffees 😉